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BMW Digest FAQ Version 4.1

Section 4: General Technical Info

Table of Contents:

4.1: Gasoline

         4.1.1:   Oxygenated gas
         4.1.2:   Octane
         4.1.3:   Fuel additives

4.2: Oil

         4.2.1:   How do i choose a motor oil?
         4.2.2:   Slick 50 and other oil additives
         4.2.3:   Synthetic oil

4.3: Coolant

4.3.1: What are the recommended coolants?

4.4: Brakes and AST

         4.4.1:   Why should i change brake fluid?
         4.4.2:   How come most of the cars dont do  brake fluid change?
         4.4.3:   How do I decide on which brake fluid to use?
         4.4.4:   What are silicone brake fluids?
         4.4.5:   Preasure bleeders
         4.4.6:   AST (All Season Traction)

4.5: AC

4.5.1: New AC regulations

4.6: Tires

4.6.1: Snow tires

4.7: Miscellaneous

         4.7.1:   Long-term car storage
         4.7.2:   Limited Slip Diff additive
         4.7.3:   Service Indicator Light Algorithm
         4.7.4:   Dual Mass Flywheels

4.1: Gasoline
4.1.1: Oxygenated gas
(by David Draper: edited)

Let me preface my comments by saying that there is an excellent article on Oxygenated gas in the February 21, 1994 issue of AutoWeek magazine. It goes into a fair amount of detail on oxy gas and the history behind it. It also tells the contents of oxy gas for several of the big oil companies.

There are currently 39 regions required to use oxy gas. It is unclear to me if the pump must specifically say the gas is oxy gas but it must say if the gas has any type of alcohol mixture in it (oxy gas).

Look on the pump and see if the gas either of the following in it: ethanol/ETBE , methanol/MTBE

If either is present chances are it is oxy gas. The maximum percetage currently allowed is 10% but ther has been talk of raising the limit to 20%.

The article in AutoWeek mentions all kinds of potential and actual problems that can be attributed to oxy gas. Some of them are hard starting, stalling, hesitation, incresed instances of vapor lock and corrosion of older engine parts. They also mention that gas mileage is decreased.

<<<<< (by John Auer:

Thanks to Harry Sidhu and Edward Bernard for their replies. The concensus seems to be:

  1. Oxygenatated fuel is mandated by the EPA in states where pollution is a problem. Smog dissipates less quickly during winter months, and the emission systems operate less effectively as well, due to the increased warmup times. Oxygenated fuels produce less emissions, helping the problem.
  2. Some gasoline suppliers will deliver gas to "regions", not "states" where the EPA has directed them to use such fuels, to make shipping easier.
  3. Oxygenated fuels can cause rough idle and hesitation problems because of their chemical nature; this, of course, isn't news to those of you using them...

(by John De Armond: edited)

It is not marked on the pump but the slightly sweet, vaguely ether-like odor of MTBE is distinctive once you've smelled it once. If your gas smells like something other than gasoline, it probably contains MTBE.

MTBE-laced gas provides less mileage than unadulterated gasoline for the same reason any other oxygenate such as methanol or nitromethane does - it carries some oxygen within its structure and that oxygen displaces a combustable atom in the molecule. If no changes are made to your engine, you will likely experience a lean-related loss of power. However, if you're willing to retune the engine, you will recognize a bit more power just as you would by adding a few percentage points of nitro. Of course, you mileage will get even worse. In effect, EPA is using a byproduct effect of hotrod fuel to (allegedly) achieve their goals.

4.1.2: Octane
(by John Dempsey:
        AKI:  Anti Knock Index- This is the average of both the Research
              and Motor Methods.  It is also what you ussually see at the

        RON:  Research Octane Number- Also known as ROM (Research Motor
              Method).  This is a real world number that is derived by
              running a single cylinder engine on a fuel sample.  The
              timing is advanced until it pings.  This advance is then
              converted to a number.

        MM:   Motor Method- Using the same engine as above, the same
              fuel sample is subjected to increased ignition timing.
              But this time, something resembling reality is used in
              in determining the number.  Load, valve timing, ect. are
              changed while the sample is being tested.  This results
              in a lower number than RON (the RON test is done at NO
              LOAD).  When you see a single, high number representing
              octane, it is usually RON (like the old days of 100 octane).

Octane: This is an organic, hydrogen-carbon structure (a ring of 8).

              Its' contribution to all this is that it was designated to
              have a value of 100 (with Heptane having a value of 0) back
              in the days when they were trying to rate and standardize
              Hence the scale became known as the Ocatane scale, and much
              confusion on subject has followed.  There is really not much
              magic to all this.  The idea was that a fuel with a rating
              of 92 could be composed of 92% Octane, and 8% Heptane.

> If I'm not mistaken, "Octane" refers to the average of AKI and RON.

Pretty close. As you can see above, AKI = (RON + MOTOR)/2. Which of course is the average of the two methods. With the advent of unleaded gas, the name Octane was replaced with the term AKI. The idea was to create less confusion, and give more meaning to the measurement.

> AKI and RON are two different rating schemes to measure the octane

It can also be seen above that the two methods of measurement are RON and MOTOR methods. Remember, the idea of measuring the "Ocatane" of a fuel was to see how much equivalent Ocatane it contained. If it measured a 92 on the scale, that meant you could build an identical fuel using 92% Ocatane molecules, and 8% Heptane molecules. Of course, this original idea of Ocatane measurement loses some its meaning when you go above 100.

> of the fuel. Seems to me there's disagreement on which to use, so > fuel manufacturers measure both, average them and call it "Ocatane",

Of the two methods, one is theoretical (RON) and the other closer to actual conditions that might be encountered (MOTOR). I don't know if that means there is a disagreement, just that they thought this method was a fair and reliable way to measure.

> which is the number printed on the pump. (Octane, that is -- my terminal

Yep. This is the Octane, or now known as AKI, of the fuel. Just pay close attention to what your manual specifies to use, and in what terms it gives it in. I've seen some that say to use 92 RON, which is much different than the number that you see on the pump these days. It is ussualy much higher.

> If you go by the manual, (89+95)/2 = 92, so 93 is fine


(by John Dempsey:

> I was wondering if you could explain to me why there is less energy in higher > octane (a.k.a AKI) gas.

The above statment is indeed true, there is less energy (BTU's per pound) in higher octane fuels than in lower octane fuels. Higher octane fuels (like octane itself) have a benzene type of structure (ring structure), while lower octane fuels have a parafine type of structure (linear chain structure). Now as too why this difference in structure has a bearing on energy content, I believe this is due to the differences in the bonds that hold the individual atoms together. There is just not as much energy stored in the ring structures. So when the molecule is oxidized, its energy state drop is less than in a lower octane molecule.

The idea to remember here is that all matter seeks its lowest energy state. The lower the energy state, the more stable it is. Also, if an atom has an oportunity to reduce its energy state, it will indeed take it (like in the combustion chamber of your engine). So a some what gaurded statement to make is that as the stability increases (high octane), you give up some energy content. This is indeed a simplified explanation.

Now the other question (if I can properly read between the lines), is if it is indeed possible to produce a fuel with a high AKI rating, and the energy content of a lower octane fuel. Yes and no. There is a range of energy content around any particular AKI rating, but there are limits. This range can be increased/decreased with the use of additives, construction, and blending. All this is relative, and I'll leave TEL, nitro, ect. out of the equation. What you should remember is to use the fuel that just meets the requirements of the engine- and that's it. This will give you the best perform- ance, and at the lowest price. And for those that claim a peformance increase when they switch to premium, well that is because you found a fuel that better matches what the engine needs. Not because you just put in some sort of wonder fuel (this is where anti-knock sensors confuse the issue).

It should also be noted that mixture quality, spark profile, and combustion chamber design are just some of the factors that affect the octane requirement. This would be another way to get the higher energy/lower octane fuels to work. Ironically, this was the reason for the design of the stratified charge engine in the earlier part of this century (so it could use the unheard of compression ratio of 6 to 1 with the low octane fuels of the time).

> I have been told several times that not only will we not get anything out of > the racing fuel (well over 103) found at race tracks, but according to some > folks I spoke to at Dinan and other places (I have the chip in my car) we > could even loose a bit of performance. Is this because (at least in part), > that the fuel ignites so slowly at these very high levels (AKI) ??

Wow. Wise folks. The reason for the loss of performance is because of the points made above. It has less energy per unit volume, you can't take advantage of it (unless you increase your compression ratio), so you are wasting your time (and money). It does have cool factor though. About the best per- formance increase you could hope for, is to convince your competitors of its merits. They fork over huge sums of money to go faster (to of course keep up with you). You go faster (because your not using it), they think it is because of the racing fuel, and it reinforces the illusion. Just don't try it with anyone that reads the list. Oh, and keep it quiet.

4.1.3: Fuel Additives
(by Robert Cottingham:

My practice has been to always use premium gas from either Shell, Mobil, Chevron, Exxon (in that order). I would never add any fuel additives. My feeling is that fuel additives are at best a waste of money unless you know what you are doing, and at worst can cause problems.

My one exception to this rule is to add Techron when pinging starts to occur. Pinging can damage the engine. Techron is the best product for cleaning the injectors which is what usually causes pinging in BMW fuel injected engines. In fact Techron was designed to address the excessive pinging problems that occured in BMWs of the early 80s. BMWs were used as the canonical engines for testing the effectiveness of this product.

However, like all fuel additives, it has its downside which is that it damages any rubber parts it comes in contact with, and it thins the oil. Therefore one should only use it when absolutely necessary (ie when pinging occurs), and then change the oil after the tank of gas to which it has been added has been burned.

If your car is properly tuned, pinging should not occur more than about once every 3000mi. It will occur alot less if you regularly get your engine up to 4000rpm. I suggest once/week at least get the car up to 4000 for at least 5mins (on non-e cars any way. I dont have enough experience with e cars to speak for these, although the pinging problem was worse on e cars in the early 80s.)

When you notice pinging, put a small bottle of Techron in at the next fill up. Put the Techron in before putting the gas in to be sure that it gets mixed well as the tank is being filled. You will need a stick or something to hold the spring loaded flap in the filler neck open while pouring in the Techron. Be careful not to spill the Techron on any rubber parts of the car or even the paint. It will definitely damage it.

If your car is pinging excessively and never had the injectors cleaned it may be necessary to repeat this treatment, but once clean, and assuming that it is driven the way a BMW was intended to be driven, this should only have to be done infrequently. And you only want to do it infrequently since its effect on the rubber parts in the fuel system is not positive.

4.2: Oil
4.2.1: How do i choose a motor oil?
< Since this article is now a FAQ posted monthly on, I no longer feel the need to put it here. I am including the header from the FAQ to give you an idea >
To help fill the never-ending search for knowledge which is USENET:-}, the following info sheet (FAQ if you wish) is being posted to and monthly. Any updated information would be greatly appreciated.


           More Than You Ever Wanted to Know About Motor Oil
                  By Ed Hackett <>

Edits: v1.0 First there was 1.0. Before that there was darkness.

       v1.1 Change in description of viscosity.
       v1.2 Updated info on AMSOIL (courtesy of Morgan McArthur

Choosing the best motor oil is a topic that comes up frequently in discussions between motoheads, whether they are talking about motorcycles or cars. The following article is intended to help you make a choice based on more than the advertising hype.

Oil companies provide data on their oils most often referred to as "typical inspection data". This is an average of the actual physical and a few common chemical properties of their oils. This information is available to the public through their distributors or by writing or calling the company directly. I have compiled a list of the most popular, premium oils so that a ready comparison can be made. If your favorite oil is not on the list get the data from the distributor and use what I have as a data base.

This article is going to look at six of the most important properties of a motor oil readily available to the public: viscosity, viscosity index (VI), flash point, pour point, % sulfated ash, and % zinc.


(Again, refer to for the full text)

4.2.2: Slick 50 and other oil additives
< from Steven J. Bernstein >

I got this article off of the Electric-Vehicle list, where friction is the enemy. 8^) (not in an EV motor, but diffs and stuff). Since there have been many discussions here asking for real statistics on these products, I hope you find it useful. It was rather long, sorry.

This was posted on

Snake Oil!
Is That Additive Really A Negative?
Article and Photos by Fred Rau
ROAD RIDER/August 1992/Pg 15

Information for this article was compiled from reports and studies by the University of Nevada Desert Research Center, DuPont Chemical Company, Avco Lycoming (aircraft engine manufacturers), North Dakota State University, Briggs and Stratton (engine manufacturers), the University of Utah Engineering Experiment Station, California State Polytechnic College and the National Aeronautics and Space Administration's Lewis Research Center.

Road Rider does not claim to have all the answers. Nor do we care to presume to tell you what to do. We have simply tried to provide you with all the information we were able to dredge up on this subject, in hopes it will help you in making your own, informed decision.

You Can't Tell The Players Without A Program

On starting this project, we set out to find as many different oil additives as we could buy. That turned out to be a mistake. There were simply too many avail able! At the very first auto parts store we visited, there were over two dozen different brand names available. By the end of the day, we had identified over 40 different oil additives for sale and realized we needed to rethink our strategy.

First of all, we found that if we checked the fine print on the packages, quite a number of the additives came from the same manufacturer. Also, we began to notice that the additives could be separated into basic "groups" that seemed to carry approximately the same ingredients and the same promises.

In the end, we divided our additives into four basic groups and purchased at least three brands from three different manufacturers for each group. We defined our four groups this way:

1.) Products that seemed to be nothing more than regular 50-rated engine oil (including standard additives) with PTFE (Teflon TM) added.

2.) Products that seemed to be nothing more than regular 50-rated engine oil (including standard additives) with zinc dialkyldithiophosphate added.

3.) Products containing (as near as we could determine) much the same additives as are already found in most major brands of engine oil, though in different quantities and combinations.

4.) Products made up primarily of solvents and/or detergents. There may be some differences in chemical makeup within groups, but that is impossible to tell since the additive manufacturers refuse to list the specific ingredients of their products. We will discuss each group individually.

The PTFE Mystery

Currently, the most common and popular oil additives on the market are those that contain PTFE powders suspended in a regular, over-the-counter type, 50-rated petroleum or synthetic engine oil. PTFE is the common abbreviation used for Polytetrafloeraethylene, more commonly known by the trade name "Teflon," which is a registered trademark of the DuPont Chemical Corporation. Among those oil additives we have identified as containing PTFE are: Slick 50, Liquid Ring, Lubrilon, Microlon, Matrix, Petrolon (same company as Slick 50), QMl, and T-Plus (K-Mart). There are probably many more names in use on many more products using PTFE. We have found that oil additive makers like to market their products under a multitude of "private brand" names.

While some of these products may contain other additives in addition to PTFE, all seem to rely on the PTFE as their primary active ingredient and all, without exception, do not list what other ingredients they may contain.

Though they have gained rather wide acceptance among the motoring public, oil additives containing PTFE have also garnered their share of critics among experts in the field of lubrication. By far the most damning testimonial against these products originally came from the DuPont Chemical Corporation, inventor of PTFE and holder of the patents and trademarks for Teflon. In a statement issued about ten years ago, DuPont's Fluoropolymers Division Product Specialist, J.F. Imbalzano said, "Teflon is not useful as an ingredient in oil additives or oils used for internal combustion engines."

At the time, DuPont threatened legal action against anyone who used the name "Teflon" on any oil product destined for use in an internal combustion engine, and refused to sell its PTFE powders to any one who intended to use them for such purposes.

After a flurry of lawsuits from oil additive makers, claiming DuPont could not prove that PTFE was harmful to engines, DuPont was forced to once again begin selling their PTFE to the additive producers. The additive makers like to claim this is some kind of "proof' that their products work, when in fact it is nothing more than proof that the American legal ethic of "innocent until proven guilty" is still alive and well. The decision against DuPont involved what is called "restraint of trade." You can't refuse to sell a product to someone just because there is a possibility they might use it for a purpose other than what you intended it for.

It should be noted that DuPont's official position on the use of PTFE in engine oils remains carefully aloof and noncommittal, for obvious legal reasons. DuPont states that though they sell PTFE to oil additive producers, they have "no proof of the validity of the additive makers' claims." They further state that they have "no knowledge of any advantage gained through the use of PTFE in engine oil."

Fear of potential lawsuits for possible misrepresentation of a product seem to run much higher among those with the most to lose.

After DuPont's decision and attempt to halt the use of PTFE in engine oils, several of the oil additive companies simply went elsewhere for their PTFE powders, such as purchasing them in other countries. In some cases, they disguise or hype their PTFE as being something different or special by listing it under one of their own tradenames. That doesn't change the fact that it is still PTFE.

In addition, there is some evidence that certain supplies of PTFE powders (from manufacturers other than DuPont) are of a cruder version than the original, made with larger sized flakes that are more likely to "settle out" in your oil or clog up your filters. One fairly good indication that a product contains this kind of PTFE is if the instructions for its use advise you to "shake well before using." It only stands to reason that if the manufacturer knows the solids in his product will settle to the bottom of a container while sitting on a shelf, the same thing is going to hap pen inside your engine when it is left idle for any period of time.

The problem with putting PTFE in your oil, as explained to us by several industry experts, is that PTFE is a solid. The additive makers claim this solid "coats" the moving parts in an engine (though that is far from being scientifically proven). Slick 50 is currently both the most aggressive advertiser and the most popular seller, with claims of over 14 million treatments sold. However, such solids seem even more inclined to coat non-moving parts, like oil passages and filters. After all, if it can build up under the pressures and friction exerted on a cylinder wall, then it stands to reason it should build up even better in places with low pressures and virtually no friction.

This conclusion seems to be borne out by tests on oil additives containing PTFE conducted by the NASA Lewis Research Center, which said in their report, "In the types of bearing surface contact we have looked at, we have seen no benefit. In some cases we have seen detrimental effect. The solids in the oil tend to accumulate at inlets and act as a dam, which simply blocks the oil from entering. Instead of helping, it is actually depriving parts of lubricant."

Remember, PTFE in oil additives is a suspended solid. Now think about why you have an oil filter on your engine. To remove suspended solids, right? Right. Therefore it would seem to follow that if your oil filter is doing its job, it will collect as much of the PTFE as possible, as quickly as possible. This can result in a clogged oil filter and decreased oil pres sure throughout your engine.

In response to our inquiries about this sort of problem, several of the PTFE pushers responded that their particulates were of a sub-micron size, capable of passing through an ordinary oil filter unrestricted. This certainly sounds good, and may in some cases actually be true, but it makes little difference when you know the rest of the story. You see, PTFE has other qualities besides being a friction reducer: It expands radically when exposed to heat. So even if those particles are small enough to pass through your filter when you purchase them, they very well may not be when your engine reaches normal operating temperature.

Here again, the' scientific evidence seems to support this, as in tests conducted by researchers at the University of Utah Engineering Experiment Station involving Petrolon additive with PTFE.

The Petrolon test report states, "There was a pressure drop across the oil filter resulting from possible clogging of small passageways." In addition, oil analysis showed that iron contamination doubled after using the treatment, indicating that engine wear didn't go down - it appeared to shoot up.

This particular report was paid for by Petrolon (marketers of Slick 50), and was not all bad news for their products. The tests, conducted on a Chevrolet six-cylinder automobile engine, showed that after treatment with the PTFE additive the test engine's friction was reduced by 13.1 percent. Also, output horsepower increased from 5.3 percent to 8.1 percent, and fuel economy improved from 11.8 percent under light load to 3.8 percent under heavy load.

These are the kind of results an aggressive marketing company like Petrolon can really sink their teeth into. If we only reported the results in the last paragraph to you, you'd be inclined to think Slick 50 was indeed a magic engine elixir. What you have to keep in mind is that often times the benefits (like increased horse power and fuel economy) may be out weighed by some serious drawbacks (like the indications of reduced oil pressure and increased wear rate).

The Plot Thickens

Just as we were about to go to press with this article, we were contacted by the public relations firm of Trent and Company, an outfit with a prestigious address in the Empire State Building, New York. They advised us they were working for a company called QMI out of Lakeland, Florida, that was marketing a "technological breakthrough" product in oil additives. Naturally, we asked them to send us all pertinent information, including any testing and research data.

What we got was pretty much what we expected. QMI's oil additive, according to their press release, uses "ten times more PTFE resins than its closest competitor." Using the "unique SX-6000 formula," they say they are the only company to use "aqueous dispersion resin which means the microns (particle sizes) are extensively smaller and can penetrate tight areas." This, they claim, "completely eliminates the problem of clogged filters and oil passages."

Intrigued by their press release, we set up a telephone interview with their Vice-President of Technical Services, Mr. Owen Heatwole. Mr. Heatwole's name was immediately recognized by us as one that had popped in earlier research of this subject as a former employee of Petrolon, a company whose name seems inextricably linked in some fashion or another with virtually every PTFE-related additive maker in the country.

Mr. Heatwole was a charming and persuasive talker with a knack for avoiding direct answers as good as any seasoned politician. His glib pitch for his product was the best we've ever heard, but when dissected and pared down to the verifiable facts, it actually said very little.

When we asked about the ingredients in QMI's treatments, we got almost exactly the response we expected. Mr. Heatwole said he would "have to avoid discussing specifics about the formula, for proprietary reasons."

After telling us that QMI was being used by "a major oil company," a "nuclear plant owned by a major corporation" and a "major engine manufacturer," Mr. Heatwole followed up with, "Naturally, I can't reveal their names - for proprietary reasons."

He further claimed to have extensive testing and research data available from a "major laboratory," proving conclusively how effective QMI was. When we asked for the name of the lab, can you guess? Yup, "We can't give out that information, for proprietary reasons."

What QMI did give us was the typical "testimonials," though we must admit theirs came from more recognizable sources than usual. They seem to have won over the likes of both Team Kawasaki and Bobby Unser, who evidently endorse and use QMI in their racing engines. Mr. Heatwole was very proud of the fact that their product was being used in engines that he himself admitted are "torn down and completely inspected on a weekly basis." Of course, what he left out is that those same engines are almost totally rebuilt every time they're torn down. So what does that prove in terms of his product reducing wear and promoting engine longevity? Virtually nothing.

Mr. Heatwole declined to name the source of QMI's PTFE supply "for proprietary reasons." He bragged that their product is sold under many different private labels, but refused to identify those labels "for proprietary reasons." When asked about the actual size of the PTFE particles used in QMI, he claimed they were measured as "sub-micron in size" by a "major motor laboratory" which he couldn't identify - you guessed it - for "proprietary reasons."

After about an hour of listening to "don't quote me on this," "I'll have to deny that if you print it," and "I can't reveal that," we asked Mr. Heatwole if there was something we could print. "Certainly," he said, "Here's a good quote for you: 'The radical growth in technology has overcome the problem areas associated with PTFE in the 1980s'"

"Not bad," we said. Then we asked to whom we might attribute this gem of wisdom. DuPont Chemical, perhaps?

"Me," said Mr. Heatwole. "I said that." QMI's press releases like to quote the Guinness Book Of Records in saying that PTFE is "The slickest substance known to man." Far be it from us to take exception to the Guinness Book, but we doubt that PTFE is much slicker than some of the people marketing it.

The Zinc Question

The latest "miracle ingredient" in oil additives, attempting to usurp PTFE's cure-all throne, is zinc dialkyldithiophosphate, which we will refer to here after as simply "zinc."

Purveyors of the new zinc-related products claim they can prove absolute superiority over the PTFE-related products. Naturally, the PTFE crowd claim exactly the same, in reverse.

Zinc is contained as part of the standard additive package in virtually every major brand of engine oil sold today, varying from a low volume of 0.10 per cent in brands such as Valvoline All Climate and Chevron l5W-50, to a high volume of 0.20 percent in brands such as Valvoline Race and Pennzoil GT Performance.

Organic zinc compounds are used as extreme pressure, anti-wear additives, and are therefore found in larger amounts in oils specifically blended for high-revving, turbocharged or racing applications. The zinc in your oil comes into play only when there is actual metal-to-metal con tact within your engine, which should never occur under normal operating conditions. However, if you race your bike, or occasionally play tag with the redline on the tach, the zinc is your last line of defense. Under extreme conditions, the zinc compounds react with the metal to prevent scuffing, particularly between cylinder bores and piston rings.

However - and this is the important part to remember - available research shows that more zinc does not give you more protection, it merely prolongs the protection if the rate of metal-to-metal contact is abnormally high or extended. So unless you plan on spending a couple of hours dragging your knee at Laguna Seca, adding extra zinc compounds to your oil is usually a waste. Also, keep in mind that high zinc content can lead to deposit formation on your valves, and spark plug fouling.

Among the products we found containing zinc dialkyldithiophosphate were Mechanics Brand Engine Tune Up, K Mart Super Oil Treatment, and STP Engine Treatment With XEP2. The only reason we can easily identify the additives with the new zinc compounds is that they are required to carry a Federally mandated warning label indicating they contain a hazardous substance. The zinc phosphate they contain is a known eye irritant, capable of inflicting severe harm if it comes in contact with your eyes. If you insist on using one of these products, please wear protective goggles and exercise extreme caution.

As we mentioned, organic zinc compounds are already found in virtually every major brand of oil, both automotive and motorcycle. However, in recent years the oil companies voluntarily reduced the amount of zinc content in most of their products after research indicated the zinc was responsible for premature deterioration and damage to catalytic converters. Obviously this situation would not affect 99 percent of all the motorcycles on the road - however, it could have been a factor with the newer BMW converter - equipped bikes.

Since the reduction in zinc content was implemented solely for the protection of catalytic converters, it is possible that some motorcycles might benefit from a slight increase in zinc content in their oils. This has been taken into account by at least one oil company, Spectro, which offers 0.02 to 0.03 percent more zinc compounds in its motorcycle oils than in its automotive oils.

Since Spectro (Golden 4 brand, in this case) is a synthetic blend lubricant designed for extended drain intervals, this increase seems to be wholly justified. Also, available research indicates that Spectro has, in this case, achieved a sensible balance for extended application without increasing the zinc content to the point that it is likely to cause spark plug fouling or present a threat to converter-equipped BMW models.

It would appear that someone at Spectro did their homework.

Increased Standard Additives (More Is Not Necessarily Better)

Though some additives may not contain anything harmful to your engine, and even some things that could be beneficial, most experts still recommend that you avoid their use. The reason for this is that your oil, as purchased from one of the major oil companies, already contains a very extensive additive package.

This package is made up of numerous, specific additive components, blended to achieve a specific formula that will meet the requirements of your engine. Usually, at least several of these additives will be synergistic. That is, they react mutually, in groups of two or more, to create an effect that none of them could attain individually. Changing or adding to this formula can upset the balance and negate the protective effect the formula was meant to achieve, even if you are only adding more of something that was already included in the initial package.

If it helps, try to think of your oil like a cake recipe. Just because the original recipe calls for two eggs (which makes for a very moist and tasty cake), do you think adding four more eggs is going to make the cake better? Of course not. You're going to upset the carefully calculated balance of ingredients and magnify the effect the eggs have on the recipe to the point that it ruins the entire cake. Adding more of a specific additive already contained in your oil is likely to produce similar results.

This information should also be taken into account when adding to the oil already in your bike or when mixing oils for any reason, such as synthetic with petroleum. In these cases, always make sure the oils you are putting together have the same rating (SA, SE, SC, etc.). This tells you their additive packages are basically the same, or at least compatible, and are less likely to upset the balance or counteract each other.

Detergents And Solvents

Many of the older, better-known oil treatments on the market do not make claims nearly so lavish as the new upstarts. Old standbys like Bardahl, Rislone and Marvel Mystery Oil, instead offer things like "quieter lifters," "reduced oil burning" and a "cleaner engine."

Most of these products are made up of solvents and detergents designed to dissolve sludge and carbon deposits inside your engine so they can be flushed or burned out. Wynn's Friction Proofing Oil, for example, is 83 percent kerosene. Other brands use naphthalene, xylene, acetone and isopropanol. Usually, these ingredients will be found in a base of standard mineral oil.

In general, these products are designed to do just the opposite of what the PTFE and zinc phosphate additives claim to do. Instead of leaving behind a "coating" or a "plating" on your engine surfaces, they are designed to strip away such things.

All of these products will strip sludge and deposits out and clean up your engine, particularly if it is an older, abused one. The problem is, unless you have some way of determining just how much is needed to remove your deposits without going any further, such solvents also can strip away the boundary lubrication layer provided by your oil. Overuse of solvents is an easy trap to fall into, and one which can promote harmful metal-to-metal contact within your engine.

As a general rule of thumb these products had their place and were at least moderately useful on older automobile and motorcycle engines of the Fifties and Sixties, but are basically unneeded on the more efficient engine designs of the past two decades.

The Infamous "No Oil" Demo

At at least three major motorcycle rallies this past year, we have witnessed live demonstrations put on to demonstrate the effectiveness of certain oil additives. The demonstrators would have a bench-mounted engine which they would fill with oil and a prescribed dose of their "miracle additive." After running the engine for a while they would stop it, drain out the oil and start it up again. Instant magic! The engine would run perfectly well for hours on end, seemingly proving the effectiveness of the additive which had supposedly "coated" the inside of the engine so well it didn't even need the oil to run. In one case, we saw this done with an actual motorcycle, which would be rid den around the parking lot after having its oil drained. A pretty convincing demonstration - until you know the facts.

Since some of these demonstrations were conducted using Briggs and Stratton engines, the Briggs and Stratton Company itself decided to run a similar, but somewhat more scientific, experiment. Taking two brand-new, identical engines straight off their assembly line, they set them up for bench-testing. The only difference was that one had the special additive included with its oil and the other did not. Both were operated for 20 hours before being shut down and having the oil drained from them. Then both were started up again and allowed to run for another 20 straight hours. Neither engine seemed to have any problem performing this "minor miracle."

After the second 20-hour run, both engines were completely torn down and inspected by the company's engineers. What they found was that both engines suffered from scored crankpin bearings, but the engine treated with the additive also suffered from heavy cylinder bore damage that was not evident on the untreated engine.

This points out once again the inherent problem with particulate oil additives: They can cause oil starvation. This is particularly true in the area of piston rings, where there is a critical need for adequate oil flow. In practically all of the reports and studies on oil additives, and particularly those involving suspended solids like PTFE, this has been reported as a major area of engine damage.

The Racing Perspective

Among the most convincing testimonials in favor of oil additives are those that come from professional racers or racing teams. As noted previously, some of the oil additive products actually are capable of producing less engine friction, better gas mileage and higher horsepower out put. In the world of professional racing, the split-second advantage that might be gained from using such a product could be the difference between victory and defeat.

Virtually all of the downside or detrimental effects attached to these products are related to extended, long-term usage. For short-life, high-revving, ultra-high performance engines designed to last no longer than one racing season (or in some cases, one single race), the long-term effects of oil additives need not even be considered.

Racers also use special high-adhesion tires that give much better traction and control than our normal street tires, but you certainly wouldn't want to go touring on them, since they're designed to wear out in several hundred (or less) miles. Just because certain oil additives may be beneficial in a competitive context is no reason to believe they would be equally beneficial in a touring context.

The Best of The Worst

Not all engine oil additives are as potentially harmful as some of those we have described here. However, the best that can be said of those that have not proved to be harmful is that they haven't been proved to offer any real benefits, either. In some cases, introducing an additive with a compatible package of components to your oil in the right proportion and at the right time can conceivably extend the life of your oil. However, in every case we have studied it proves out that it would actually have been cheaper to simply change the engine oil instead.

In addition, recent new evidence has come to light that makes using almost any additive a game of Russian Roulette. Since the additive distributors do not list the ingredients contained within their products, you never know for sure just what you are putting in your engine.

Recent tests have shown that even some of the most inoffensive additives contain products which, though harmless in their initial state, convert to hydrofluoric acid when exposed to the temperatures inside a firing cylinder. This acid is formed as part of the exhaust gases, and though it is instantly expelled from your engine and seems to do it no harm, the gases collect inside your exhaust system and eat away at your mufflers from the inside out.

Whatever The Market Will Bear

The pricing of oil additives seems to follow no particular pattern whatsoever. Even among those products that seem to be almost identical, chemically, retail prices covered an extremely wide range. For example:

One 32-ounce bottle of Slick 50 (with PTFE) cost us $29.95 at a discount house that listed the retail price as $59.95, while a 32-ounce bottle of T-Plus (which claims to carry twice as much PTFE as the Slick 50) cost us only $15.88.

A 32-ounce bottle of STP Engine Treatment (containing what they call XEP2), which they claim they can prove "outperforms leading PTFE engine treatments," cost us $17.97. Yet a can of K Mart Super Oil Treatment, which listed the same zinc-derivative ingredient as that listed for the XEP2, cost us a paltry $2.67.

Industry experts estimate that the actual cost of producing most oil additives is from one-tenth to one-twentieth of the asking retail price. Certainly no additive manufacturer has come forward with any exotic, high-cost ingredient or list of ingredients to dispute this claim. As an interesting note along with this, back before there was so much competition in the field to drive prices down, Petrolon (Slick 50) was selling their PTFE products for as much as $400 per treatment! The words "buyer beware" seem to take on very real significance when talking about oil additives.

The Psychological Placebo

You have to wonder, with the volume of evidence accumulating against oil additives, why so many of us still buy them. That's the million-dollar question, and it's just as difficult to answer as why so many of us smoke cigarettes, drink hard liquor or engage in any other number of questionable activities. We know they aren't good for us - but we go ahead and do them anyway.

Part of the answer may lie in what some psychiatrists call the "psychological placebo effect." Simply put, that means that many of us hunger for that peace of mind that comes with believing we have purchased the absolute best or most protection we can possibly get.

Even better, there's that wonderfully smug feeling that comes with thinking we might be a step ahead of the pack, possessing knowledge of something just a bit better than everyone else.

Then again, perhaps it comes from an ancient, deep-seated need we all seem to have to believe in magic. There has never been any shortage of unscrupulous types ready to cash in on our willingness to believe that there's some magical mystery potion we can buy to help us lose weight, grow hair, attract the opposite sex or make our engines run longer and better. I doubt that there's a one of us who hasn't fallen for one of these at least once in our lifetimes. We just want it to be true so bad that we can't help ourselves.

Testimonial Hype vs. Scientific Analysis

In general, most producers of oil additives rely on personal "testimonials" to advertise and promote their products. A typical print advertisement will be one or more letters from a satisfied customer stating something like, "1 have used Brand X in my engine for 2 years and 50,000 miles and it runs smoother and gets better gas mileage than ever before. I love this product and would recommend it to anyone."

Such evidence is referred to as "anecdotal" and is most commonly used to pro mote such things as miracle weight loss diets and astrology.

Whenever I see one of these ads I am reminded of a stunt played out several years ago by Allen Funt of "Candid Camera" that clearly demonstrated the side of human nature that makes such advertising possible.

With cameras in full view, fake "product demonstrators" would offer people passing through a grocery store the opportunity to taste-test a "new soft drink." What the victims didn't know was that they were being given a horrendous concoction of castor oil, garlic juice, tabasco sauce and several other foul-tasting ingredients. After taking a nice, big swallow, as instructed by the demonstrators, the unwitting victims provided huge laughs for the audience by desperately trying to conceal their anguish and disgust. Some literally turned away from the cameras and spit the offending potion on the floor.

The fascinating part came when about one out of four of the victims would actually turn back to the cameras and proclaim the new drink was "Great" or "Unique" or, in several cases, "One of the best things I've ever tasted!" Go figure.

The point is, compiling "personal testimonials" for a product is one of the easiest things an advertising company can do - and one of the safest, too. You see, as long as they are only expressing some one else's personal opinion, they don't have to prove a thing! It's just an opinion, and needs no basis in fact whatsoever.

On the other hand, there has been documented, careful scientific analysis done on numerous oil additives by accredited institutions and researchers.

For example:
Avco Lycoming, a major manufacturer of aircraft engines, states, "We have tried every additive we could find on the market, and they are all worthless."

Briggs and Stratton, renowned builders of some of the most durable engines in the world, says in their report on engine oil additives, "They do not appear to offer any benefits."

North Dakota State University conducted tests on oil additives and said in their report, "The theory sounds good - the only problem is that the products simply don't work."

And finally, Ed Hackett, chemist at the University of Nevada Desert Research Center, says, "Oil additives should not be used. The oil companies have gone to great lengths to develop an additive pack age that meets the vehicle's requirements. If you add anything to this oil you may upset the balance and prevent the oil from performing to specification."

Petrolon, Inc., of Houston, Texas, makers of Petrolon and producers of at least a dozen other lubrication products containing PTFE, including Slick 50 and Slick 30 Motorcycle Formula, claim that, "Multiple tests by independent laboratories have shown that when properly applied to an automotive engine, Slick 50 Engine Formula reduces wear on engine parts. Test results have shown that Slick 50 treated engines sustained 50 percent less wear than test engines run with premium motor oil alone."

Sounds pretty convincing, doesn't it? The problem is, Petrolon and the other oil additive companies that claim "scientific evidence" from "independent laboratories," all refuse to identify the laboratories that conducted the tests or the criteria under which the tests were conducted. They claim they are "contractually bound" by the laboratories to not reveal their identities.

In addition, the claim of "50 percent less wear" has never been proven on anything approaching a long-term basis. Typical examples used to support the additive makers' claims involve engines run from 100 to 200 hours after treatment, during which time the amount of wear particles in the oil decreased. While this has proven to be true in some cases, it has also been proven that after 400 to 500 hours of running the test engines invariably reverted to producing just as many wear particles as before treatment, and in some cases, even more.

No matter what the additive makers would like you to believe, nothing has been proven to stop normal engine wear.

You will note that all of the research facilities quoted in this article are clearly identified. They have no problem with making their findings public. You will also note that virtually all of their findings about oil additives are negative. That's not because we wanted to give a biased report against oil additives - it's because we couldn't find a single laboratory, engine manufacturer or independent research facility who would make a public claim, with their name attached to it, that any of the additives were actually beneficial to an engine. The conclusion seems inescapable.

As a final note on advertising hype versus the real world, we saw a television ad the other night for Slick 50 oil additive. The ad encouraged people to buy their product on the basis of the fact that, "Over 14 million Americans have tried Slick 50!" Great. We're sure you could just as easily say, "Over 14 million Americans have smoked cigarettes!"-but is that really any reason for you to try it? Of course not, because you've seen the scientific evidence of the harm it can do. The exact same principle applies here.

In Conclusion

The major oil companies are some of the richest, most powerful and aggressive corporations in world. They own multi-million dollar research facilities manned by some of the best chemical engineers money can hire. It is probably safe to say that any one of them has the capabilities and resources at hand in marketing, distribution, advertising, research and product development equal to 20 times that of any of the independent additive companies. It therefore stands to reason that if any of these additive products were actually capable of improving the capabilities of engine lubricants, the major oil companies would have been able to determine that and to find some way to cash in on it.

Yet of all the oil additives we found, none carried the name or endorsement of any of the major oil producers.

In addition, all of the major vehicle and engine manufacturers spend millions of dollars each year trying to increase the longevity of their products, and millions more paying off warranty claims when their products fail. Again, it only stands to reason that if they thought any of these additives would increase the life or improve the performance of their engines, they would be actively using and selling them - or at least endorsing their use.

Instead, many of them advise against the use of these additives and, in some cases, threaten to void their warranty coverage if such things are found to be used in their products.

In any story of this nature, absolute "facts" are virtually impossible to come by. Opinions abound. Evidence that points one direction or the other is avail able, but has to be carefully ferreted out, and is not always totally reliable or completely verifiable.

In this environment, conclusions reached by known, knowledgeable experts in the field must be given a certain amount of weight. Conclusions reached by unknown, unidentifiable sources must be discounted almost totally. That which is left must be weighed, one side against the other, in an attempt to reach a "reasonable" conclusion.

In the case of oil additives, there is a considerable volume of evidence against their effectiveness. This evidence comes from well-known and identifiable expert sources, including independent research laboratories, state universities, major engine manufacturers, and even NASA.

Against this rather formidable barrage of scientific research, additive makers offer not much more than their own claims of effectiveness, plus questionable and totally unscientific personal testimonials. Though the purveyors of these products state they have studies from other independent laboratories supporting their claims, they refuse to identify the labs or provide copies of the research. The only test results they will share are those from their own testing departments, which must, by their very nature, be taken with a rather large grain of salt.

Sidebar: Synthetic Oils

Whenever we talk about oil additives, the subject of synthetic oils inevitably crops up. Actually, the tow subjects have very little to do with each other, but since many riders seem to equate additives and synthetics together in their minds, we will take a few lines just to clear the air.

Synthetic oils were originally developed for use in gas turbine engines. In most cases they are capable of maintaining their viscosity for longer periods of use and under much greater temperatures and pressures than petroleum products. Commons synthetics used for engine lubrication today are Polyalphaolefin (like Mobil 1) or Dibasic Organic Esters (like AMSOIL). They are fully compatible with conventional oils and can be mixed, providing their ratings match.

Probably the best situation is a blend of synthetics and mineral oils, such as Golden Spectro and AGIP Sint 2000. These products seem to offer the best of both worlds in protection and extended service life. They may cost considerably more than standard petroleum products, but they also can be used for much longer periods between oil changes without losing their protective capabilities.

Synthetics and synthetic blends offer a wider range of protection than standard petroleum products. However, it should be noted that this extended range of protection reaches into an area of temperatures and pressures virtually impossible to attain inside most motorcycle engines and transmissions. In other words, if you use them, you are buying a sort of "overkill protection." It's certainly not going to hurt anything - it's just unnecessary. That is, unless it makes you feel better knowing the extra protection is on board, in which case the added expense may be well justified.

As a basic rule of thumb, using the standard engine oil recommended by your bike's manufacturer and changing it about every 3000 miles will afford you all the protection you'll ever need. But if you feel better knowing you have more protection than you need or, if you like the extended service-life feature, there's certainly nothing wrong with using a premium grade synthetic blend lubricant.

4.2.3: Synthetic Oils
From: (Garrett McWilliams) Date: Tue, 22 Nov 1994 14:20:23 +0500

This came through on the RX-7 list. FYI >
>: Nothing shuts an engineer up quicker than hard data. >:
>: Keep in mind as you read this that I used to develop lubricating oil >: *additives* and not the finished oil. All the people I used to work >: with were of the mind that the base oil is merely there to carry the >: additives. Of course, we'd whip up finished oils using these >: additive packages to carry out engine tests and field tests. Even the >: senior engineers pretty much all used high quality naturals in their >: personal vehicles. We all have always believed that oil cleanliness >: and a decent additive package were the foremost concerns in oil >: performance.
>: In the quest for knowledge (not to mention I just dumped a shitload >: of work on my prof's desk and can screw off for the next week), I >: decided to try out one of those newfangled search engines over at our >: engineering library. I did a search on synthetic oils and got quite >: a few hits.
>: Now, try to keep your cheering down. Don't bother to light up the >: flame units as traffic on the internet is already getting pretty >: high and I think the following could have the most profound impact >: on the net since Robert Morris 'accidentally' released his virus. >:
>: I was wrong. (feel free to replace 'wrong' with the adjective of >: your choice)
>: One of the hits on my literature search was: >:
>: Synthetic Automotive Engine Oils PT-22 >: (selected papers through 1981)
>: Prepared under the auspices of the Fuels & Lubes committee of SAE. >:
>: An underlying theme ran through all the included papers: >: * improved wear (data)
>: * improved oxidation (data)
>: * improved deposits (data)
>: Most of the papers included experimental data (bench, engine, and field >: tests. A number of the papers seem to indicate that while the wear >: properties of the synthetic base stocks are somewhat better than the >: natural base stocks, they respond *much* more to additization than the >: naturals, resulting in *significant* performance benefits (yes, yes, at >: pressures and temperatures lower than those at the cores of neutron >: stars).
>: A number of them also mentioned that the dispersancy of the synthetics >: was not significantly different than the naturals. (I guess additives >: are good for something) Never underestimate the importance of a good >: dispersant.
>: Virtually all the papers mention the cost effectiveness issue. Whether >: synthetics are cost effective in your application depends on lot of >: factors. Since only about 2% of the crude can be made into base stock >: for lube oils, a lot of work is going into less expensive processes >: for making synthetics, which can be synthesized from much more of the >: crude. Thus the price of synthetics is dropping (relative to the >: naturals) and is expected to drop much more in the future. >:
>: Still, I feel that since the oil makers are really only concerned >: about getting API certifcation, they probably tend to dose their >: synthetics lighter than their naturals. If it makes SH/CE (or >: whatever) why waste the additive?
>: Hell, I might even try Mobil-1 in my Nighthawk at the next oil change. >:
>: This is the last you'll hear this washed-up lubrication engineer >: say anything disparaging synthetic oils. Again, try to contain >: your enthusiasm. If you're looking at a color terminal you might even >: be able to see the redness in my face. >:
>: (I'm lucky I don't live in Singapore! :-) ) >:

4.3: Coolant
4.3.1: What are the recommended coolants?

BMW coolant if you want to spend the money, otherwise:

(by Jim Conforti:
                Zerex           0.1 mg/cm^2/wk corrosion
                Award           0.2
                Pronto          0.2
                Trust           0.3
                Pah-Nol         0.4
                Texaco          0.4
                Recycled        0.6
                Prestone        0.7


                Crown            8.4
                Shellzone       10.2
                Peak            11.9    <- this one's sold everywhere...
                Fleetline       12.6
                UniGard         12.8
                Beaver          13.5
                MacGuard        15.0
                Sure            19.7
                500XL           20.0

4.4: Brakes and AST
4.4.1: Why should i change brake fluid?
(by Kinports Brian:

The main reasons brake fluid requires regular changing is internal contamination and water mixed in the system. Contamination comes from any number of sources from calipers to brake lines to master cylinders, etc. Brake fluid is hydroscopic (absorbs water). The older brake fluid gets the more water it can absorb particularly in wetter climates as one person suggested.

This water/brake fluid will easily boil under continual hard braking conditions. When this happens, air (boiled water) is now in the brake system, pand this air is compressible. In the extreme case, when you push the brake pedal, it will go all the way to the floor compressing the air without providing firm breaking.


My advice is to change your fluid yearly regardless of the car you are driving or how often you use the car. I change mine probably 2-4 times a year just before track events.

(by Pete Read <>)

Terry Lee asks:
>On Brake Fluid rating, what is meant by dry and wet boiling point? >And why would you know which one pertains to your application >at any given time?


Brake fluid is hydroscopic (absorbs water). When fresh from the can, it can be considered "dry" with the higher boiling point. That's why racers and people doing driver's schools change the brake fluid just before events. Over time, brake fluid absorbs water lowering its boiling point to the "wet" level.

For street cars, wet boiling point numbers are more important than dry because the fluid stays in for quite a while (one to two years). After a few months, with exposure to humid air, the brake fluid performance is probably closer to the wet than dry point.


Brake fluid needs to be changed for two reasons, maintenance and performance (it takes about a quart to flush the system).

Maintenance - changing old brake fluid removes water from the brake system. Brake fluid is hydroscopic, it absorbs water. Old brake fluid must be flushed out or water absorbed by the fluid eventually causes internal rust on the disk calipers and pistons.

Performance - changing old brake fluid helps high temperature operation because fresh (dry) brake fluid has a higher boiling point than older (wet) brake fluid. If brake fluid boils, compressible gas bubbles form, resulting in a very spongy brake pedal.

DOT Brake Fluid Specs

                    DOT 3  DOT 4  DOT 5
                    -----  -----  -----

Dry Boiling Point 401F 446F 500F
Wet Boiling Point 284F 311F 356F

The DOT 3 and DOT 4 specifications are for glycol based (regular) brake fluid, while DOT 5 is for silicone.

4.4.2: How come most of the cars dont do brake fluid change?
(by Rick Kjeldsen:

I can think of a couple of reasons for this:

  • The typical car sold in the US is designed for the average American driver doing 60 to 65 on the highway and never really pushing it. The specs of old (wet) brake fluid are probably just fine for that application. As a data point, before I took over maintenance on my wife's cars, she never had her brake fluid changed, and never had a problem. But the first time I "soloed" in her Rx7 and fooled around a little, I felt the brakes fade.

    BMWs, on the other hand, are performance oriented cars, designed to be driven at speed on the Autobahn, and often praised for their good brakes.

  • There is a trade-off between high temp performance and suseptability to moisture in brake fluids. The performance fluids tend to have lower wet boiling points. BMW's recomended fluid is pretty good, it has a higher dry boiling point than most dealer fluids I've looked at (with a few exceptions). It may be theirs is also more suseptable to moisture.
  • I think BMW is unusual in how much technical info they put in the owners manual. On other cars I've owned this kind of info is in the shop manual, not the owners manual. The owners manual just says to have "maintenance" done every so many miles, not what should be done. Most people who own appliance cars don't have the shop manual, so even if the manual recomended changing the fluid, the owner would never know it.
  • One of the selling points of modern cars is low maintenance. That isn't accidental, companies work hard at it and IMO often trade-off good maintenance practices for it. Witness 100k mile tune-up intervals and 15k mile oil change intervals. If not changing the fluid won't cause brake system problems till after the warranty runs out, and the old fluid leaves an adequate margin of saftey for the average driver, why should they increase maintenance costs by recomending it be changed? (Lawsuits? No chance. Even old fluid is good enough to work till you start to push the car. That gives the lawyers room to argue that you were driving in an unsafe manner, so the car company is not at fault. Plus boiled brakes have this nice characteristic of coming back when they cool, not as good as new but good enough. Just TRY to convince an auto-ignorant jury that the brakes really didn't work when you tried to stop, but worked an hour later when the police tried them.)

4.4.3: How do I decide on which brake fluid to use?
(by Pete Read <>)


  1. Normal Driving - Castrol LMA (Low Moisture Absorption), DOT 4, 446F dry and 311F wet boiling points, about $5 per quart, changed every year or two.
  2. Driver's schools (brakes at very high temp) - ATE Super Blue, DOT 4 spec, 536F dry and 392F wet boiling points, about $11 per quart, changed before every driver's school if it's more than a month old. In my case, about three changes a year for five or six schools. ...

(by richard

as far as why one fluid is better than another, it's mostly a boiling point issue: if you're changing the fluid a lot, go for the high dry boiling point. if you're not changing the fluid a lot, go for the high wet boiling point (remembering that brake fluid starts out "dry" and ends up "wet" after enough time has passed.) changing the fluid "a lot" means several times a year for us track weenies; the high heat of the track is tough on brakes and brake fluids.

as for the infamous Silicone fluids (usually confused with DOT-5 because for a long time the only fluids that could meet the DOT-5 requirements were Silicone based), they are a good choice for occasionally driven restorations where the entire brake system has been rebuilt with new rubber. using them in a track-driven car is highly questionable, as is using them in any car whose brake system has glycol-impregnated rubber in it (that is, most any car on the road.) there are supposed to be glycol-based DOT-5 fluids around, but they are certainly not yet common. i would expect a glycol-based DOT-5 fluid to be a very nice dual purpose street/track brake fluid.

4.4.4: What are silicone brake fluids?
(by Richard Welty:

well, silicone fluid can be an excellent choice for an older car which is undergoing a complete brake system renovation and which will not be seeing heavy service.

other than that, it's not necessarily a good idea, especially in cars which are seeing service at driving schools such as those offered by the bmw club. also, it is a particularly bad idea in ABS systems

  • -- i'm not sure of the reasons, but i note that nearly every car with ABS has an explicit warning against silicone fluids in the brake system.

first of all, silicone is difficult to pour cleanly; it will always have a little air in it, and the pedal will always be a little spongey.

one of its supposed advantages is a higher dry boiling point; what is not generally publicized is that unlike glycol based fluids, silicone fluids become compressible independently of boiling, and at a lower temperature than they boil at. thus, the higher dry boiling point is merely a technicality that doesn't actually do much in practice.

one good feature of silicone fluids is that they don't trash paint, although it is possible that if left on paint they may cause "fisheyes" when the time comes to repaint the car (but i'm not sure on this point; it is merely speculation based on what silicone based car "waxes" do when repaint time comes around.)

while they do not absorb water, neither do they keep it out of the brake lines; a well sealed brake system is still necessary as the water will simply pool up and rot out the brake lines in a localized fashion with silicone fluids.

they are _not_ compatible with DOT-3 and DOT-4 fluids; you must switch completely if you switch at all. since everybody i know at the track uses Castrol LMA or other similar high quality fluid, somebody using silicone fluids had better look to their own sources of supply (allison and i once borrowed a bottle of LMA from Klaus the infamous Roundel photographer at a Mid-Ohio track event once. can't do that if you need silicone fluid.)

there is some indication that DOT-5 fluids based on Glycol may appear soon; if so, these would become the prefered fluids for street cars at track events, i should think.

(by Ben Thongsa:

Silicone brake fluid has the advantages over regular brake fluid of being non-water absorbing, doesn't attack paint, and has a higher boiling point than most regular brake fluids.

The disadvantages are that the fluid tends to trap tiny air bubbles more easily, is more compressible than regular fluids, and doesn't absorb water. Not absorbing water can be a disadvantage because if there is water trapped in the system, it will settle out in the lowest points, causing rust or possibly freezing.

I believe BMW says not to use silicone fluid in ABS-equipped cars. This is probably due to the compressibility of the fluid. The ABS pump would have to work harder when activated to keep pressure in the lines.

I personally would use good DOT 4 fluids in all but antique/show cars. Silicone fluid would be acceptable for those because it wouldn't attack the paint and if installed properly, would help keep the hydraulics from rusting.

Date: Sat, 14 Jan 1995 03:03:11 -0500

Following are comments from an ITT/Teves (OEM brake supplier) employee to questions I posed on Ate Super Blue brake fluid...


  • Message follows **********

Date: Fri, Jan 13, 1995 11:30 AM PST
Subj: 3-series brake info.

Ate brake fluid is glycol based. We at ITT take a rather dim view of silicone based brake fluids; the compatibility between your ABS and silicone brake fluid is not the greatest. It turns out that the hydraulic control unit of your ABS was designed to work with conventional (DOT 3 and DOT 4) fluids; silicone fluids can affect the sealing performance of some of the internal valves over time. By the way, the same applies for other ABS units (Bosch, etc.) too: Use only DOT 3 or DOT 4 brake fluid (DOT 5 is the silicone fluid). DOT 4 is similar to DOT 3, with the only real difference being a slightly higher boiling temperature with DOT 4. Any brand name DOT 3 or 4 fluid is fine. The newer the can, the better, and don't leave the can open in your garage -- it will soak up moisture from the air. (That's why you always see the warning "use only brake fluid from a sealed container") ...

4.4.5: Preasure bleeders
Rick wrote:
> BTW, anybody have any experience with the Eze-Bleed (sp?) > fromAutoExperts? It's a cheep ($30) preasure bleeder that works > off aspare tire. I was thinking about trying one to see if it > takes someof the fussing out of the job.

I flushed out my system a couple weeks ago with the Eezibleed. It was quick, clean and infinitely easier than pumping the pedal or trying to use a mityvac-type suction pump. Just be aware that Auto Expert Products (800-795-6958) doesn't take credit cards if you decide to order one.


Building a Pressure Brake Bleeder

Date sent:        Thu, 11 Jan 1996 13:48:36 -0600

Attached are 2 articles describing a pressure bleeder

( many thanks to Jon Lindsay ) you can make at home, assuming you have tools to drill holes in 1/4" metal and 5/8" plastic. A vice helps a lot too. The articles mention a 1/2 gallon tank which is more accurately a 2 liter tank. The cap needed for the fluid reservoir on the car comes with a 500ml jar. Both containers are made of plastic and are sold under the brand name Nalgene. I found them at Erehwon, an outdoor outfitter.
The plastic tubing referred to as 5/16" OD and 3/8" OD is vinyl, the 1/4" OD tubing is PVC. I found all at an ACE hardware store.
The tire stems I found were Camel brand nbr. 30-445 at Track Auto. No one store had 4 of them on the rack at one time. I visited 3 stores. An alternate to 30-445 might be nbr. 30-463. I found this after I built mine.

Price list -
stems/valves, 30-445 11.96 (4 x 2.99) OR alternate?, 30-463 7.96 (4 x 1.99)

tubing                    1.40
500ml jar with #3 cap     1.90
2000ml jar                7.50
1 quart jar               3.90

Read on and have fun!

Al Cote '92 325i

  • Article 1 ============================ >From bmw-digest.v3.n536 Thu, 3 Aug 1995 23:01:59 -0400 From: Subject: Re: Brake Bleeders

I fabricated a pressure (not vacuum) bleeder out of a couple of sturdy plastic tanks (1/2 gal supply, 1 qt waste), tire valves, and hose. The unit fits onto the reservoir, uses 10# of pressure and has none of the leak problems which the vacuum units seem to be plagued with. It is not that expensive (<$20), works well, and looks like it is professionally made. The main tank is from an outdoor outfitter, takes the pressure, and I was able to find a cap at the same store which fit the reservoir (so I didn't have to buy from the dealer a BMW reservoir cap). I seal it off after bleeding and am ready to go next time. If anyone wants more detailed instructions let me know. Wife and kids no longer have to deal with the up-down routine.

'84 633 CSi

  • Article 2 ============================

>From! Sat Aug 5 >08:58:02 1995
Date: Sat, 5 Aug 1995 08:12:53 -0400
Subject: Brake Bleeder

I received a number of inquiries about the brake bleeder and not having a lot of confidence in net graphics I'll try to describe the setup with words. If it is not clear or if you have questions, just drop a note. If you are hopelessly befuddled by my directions, give me a mailing address and I'll send you a diagram. Here goes:

PRINCIPLE: Push fluid into the reservoir at pressure to force the old fluid out the caliper nipples rather than suck it out from the nipples. Brake systems are pressure systems and are better able to deal with even this small pressure than a vacuum system which will always suck a little bit of air in at the nipple.


  1. 1 each-- 1/2 gallon heavy duty (Nalgene) plastic tank. I bought one from Hudson Bay Outfitters, a local dealer of outdoor equipment. They had many different styles and shapes. My criteria were a) a good tight seal on the screw cap, b) very solid construction, and
  2. a relatively flat surface area on the top where I could mount a metal tire valve. The dimensions of the tank I bought were 8"(h)x6"(w)x3"(d). I think it is most important that it be sturdy and that most of the volume be air rather than fluid so that the pressure remains relatively constant during the bleed, I use Ate Super Blue and put about a half quart in the tank. This tank was the most expensive part ~ $9.50
  3. 1 each-- 1quart tank into which old fluid is collected. You have probably used a form of this in the past. At the same same outfitter store I got a lighter duty quart jug for this purpose, put another tire valve in the cap, drilled the valve out with a 1/4" bit, and ran a 5/16" hose from the caliper nipple over a short section of stiff 1/4" tubing which goes through the valve and down into the tank. A very small hole drilled into the cap next to the valve will allow air to escape. No more catching fluid in a wine bottle, if this one falls over it is no problem, because for all intents and purposes it is a single piece.
  4. 1 each-- Nalgene cap to temporarily fit the top of the reservoir in place of the existing one with the sending unit. I found a Nalgene cap about 1 3/4" in diameter which fit my old 633 perfectly (a tight fit here is essential). This part may take some trial and error and the cap from one reservoir may be different from another.
  5. 2 feet of 3/8" OD x 1/4 ID vinyl hose-- to go from A above to the cap C.
  6. 2 feet of 5/16" OD hose to drain the fluid into B.
  7. 9" of stiff 1/4" OD tubing to fit inside the tank A from the drilled valve down to a corner in the tank (take a look at the pesticide tank in your garage if you can't visualize this).
  8. 4 metal type screw valve stems-- I bought them at Track Auto, drilled out three of them as described in B above. The fourth one is mounted in the cap of A above and is used to pressurize the system (in other words don't drill this one out).

Drill out three of the four valves with 1/4" bit (be careful and use a vise).
Drill out all three caps to accept the valves as well as a spot on the
shoulder of tank A. Mount undrilled valve in cap of Tank A. Insert 1/4" stiff tubing into bottom end of one remaining valve and mount valve on shoulder of Tank A. Mount a remaining drilled valve into hole in cap which mounts on reservoir. Put 3/8" OD hose on the two valve stems just described.
Collector tank construction is described above. I have a small electric
pump but a hand pump will do. I wouldn't pressurize above 10 to 15 psi.
Larger hoses will improve flow and a stop cock valve allows you to fine tune
your setup but is not necessary. A local observer suggested a strap for the reservoir to ensure your reservoir doesn't decide to lift off, another unnecessary precaution in my experience. You don't have to do anything while it is bleeding (as usual, one at a time), but you might try applying a bit of pressure to the brake pedal to get things moving.

Put about a half quart of your favorite fluid into Tank A and tighten lid.
Replace cap on reservoir with Cap C and make sure you have a good seal. Pressurize Tank A, look for leaks ( I have never found any) and open your
caliper nipples in the traditional fashion. After you are finished, release the pressure in the tank by pushing down on the valve release... then remove the caps. Have fun.

This is not as difficult as it may seem, I just wanted to be as detailed as possible. The directions are lengthy so I decided not to post. But I have gotten about 20 inquiries. Your thoughts?

Jon Nelson
'84 633CSi

4.4.6: AST (All Season Traction)
From: Jim Conforti <>
Date: Wed, 22 Feb 1995 13:12:46 -700 (MST)

ASC+T or Anti-Skid Control + Traction ...

now AST or All-Season Traction in marketing-speak ;)

Is a system controlled by your ABS unit ..

What basically happens is that by reading the pulses from the wheel hubs (ABS, 48/rev) the ABS CU can determine if slip is occuring at the rear wheels under power ..

If slip (traction loss) is detected, the ABS CU then can

  1. APPLY the brake to the slipping wheel
  2. SIGNAL the DME to reduce torque by retarding timing (INTERVENTION)
  3. CLOSE the throttle partially .. it does this by EITHER
    1. SIGNALLING the EML unit (Elec. Throttle Control / Fly-By-Wire)
    2. CLOSING a secondary throttle plate upstream of the "real" one

(Which depends on the car .. 3'ers use b ... 8's use a)

There are more subtle nuances to speak of also ... like if the car is an AT (AEGS) car and a shift is about to occur, and the wheels are slipping, the Trans. CU is signalled to postpone the upshift ..

This is my understanding as explained by John Patton (One of NA's almighty high tech-guru/managers and all-round decent guy) .. he came out to the CCA Driving Events Conference in Dallas and brought us some neato handouts

FWIW, My wife's car has AST (then ASC+T ;) and for *normal* street driving in nasty conditions it is 110% wonderful!! ... With AST on and studded snows on all 4 corners, we can go ANYWHERE in winter! .. and Utah winters get REAL icy and nasty ..

On the M3, Pirelli W210's and the 25% LSD do a good job of keeping me going when even FWD and 4WD vehicles have a tough time .. and I'm SURE that something somewhere in the suspension helps along .. I have never owned an RWD car more poised in the snow .. IF I COULD ONLY GET STUDDABLE TIRES ;)

(I could change Landshark to SNOWshark) :) :) :)

Hope this explaination helps .. any interested CCA'er should find out from their chapter pres. who went to the conf. and then "borrow" that BMW NA produced booklet on Advanced Vehicle Systems .. it's a real good read!

Jim Conforti

4.5: AC
4.5.1: New AC regulations
(by Charles ?:

There are many posts on R-12 on the Mopar list, which I can probably forward to this list if anyone's interested. The big problems with trying to use R-134a are: wrong expansion valve, too small a condenser, different refrigerant oil. This last is apparently the most serious. R-134a does not use the same type of oil because it does not dissolve in the (R-12) mineral oil. unfortunately, the rubber parts in your system (unless newer than about '89) are not compatible with the new oil. This means changing every gasket, O-ring, AND COMPRESSOR seal. I have also read that even traces of the old R-12 will cause the new so-called P.A.G. oils to break down and ruin your compressor (in a catalytic reaction much like the alleged effect of R-12 on ozone).
Bottom line seems to be: DON'T put 134 in a 12 system; you CAN buy R-12, if willing to spend $200 at once.

(by Richard Welty: and as John DeArmond. has pointed out (below, Ed.), there are other R-12 alternatives that may be cheaper and more effective than R-134a; they were briefly banned during the Bush administration for non-technical reasons, but in a fit of sanity the Clinton EPA has actually reversed that position. i'd definitely NOT rush into a R-134a conversion at this time.
(by (John De Armond))

> I've got an A/C system for a 2002 sitting in my garage that will probably > never get installed. The reason is that I don't want to deal with the > R12 thing in the future. According to a guy hear at work that knows a > great deal about refrigeration systems, the older style systems (up to the > mid '70s I think) have an expansion valve setup that won't work with the > new R134.

This not true. R-134a works a bit better if the superheat is adjusted via the hex screw inside the valve exit port but that isn't absolutely necessary. And if you do decide to change the valve, it is only about $20. BFD. Of vastly more concern for ANY system converted to 134a is the incompatability of the PAG oil with even traces of old refrigerant. Supposedly other types of oils that are compatable with traces of old refrigerant are under development but the only ones shown to date, the esters, are so sensitive to moisture that the moisture typically present in the dryer will cause it to break down. Plus it is a lousy lubricant. As of now, you MUST change everything that is porous and has been in contact with the old refrigerant. That includes the hoses, the dryer, all O-rings and seals and the evaporator if it has any elastomer seals. And as a practical matter, a compressor replacement is in order unless you want to take it completely apart to scrub the components and replace the gaskets.

Conversion is really a side issue because R-12 is going to be around for a long time. The Bush admin EPA was shilling for big industry as represented by MACS and SAE. The Clinton EPA is taking a much more pragmatic approach (strangely enough), particularly after the industry was caught lying about the ease of conversion and the reliability of 134a systems. They have already pushed back the deadline to stop production of R-12 by a year and the feeling is it will be pushed back further. Plus there are alternatives. R-406a, formerly known as GHG-12, developed by George Goble ( is an exact drop-in for R-12. Banned at industry request under the Bush admin, it was re-examined under the Clinton administration and given approval for everything except mobile use. The exception is strictly a political move in that the EPA doesn't want to admit all at once how bad it screwed up so the mobile exclusion will go away within the year. This blend has over 4 years' testing in thousands of vehicles and works fine. It even improves the cooling capacity of systems it is used in. Meanwhile, you can buy this blend from People's Welding in Indianapolis (try 800 info for the number - I don't have it handy) and once you own it, you can use it as you wish, including in your car.

Another alternative, OZ-12, was banned because MACS stirred up media hysteria because it is flammable (mix of propane and isobutane). A rational evaluation of the risks (a pound of this stuff right beside a hundred lbs of gasoline) was never considered. Reliable rumor has it that OZ-12 is about to re-appear with a fire supression additive that makes it non-flammable. Like 406a, OZ-12 slightly improves the performance of the system and is completely compatable with and can be mixed with R-12.

Finally, if all else fails, you can mix your own refrigerant using isobutane (NOT butane) camp stove fuel (22%) and propane (78%). There is simply no way someone with a little ingenuity and motivation will ever be without AC. I assume that if you're clever enough to install the system, you can use one of these alternatives.

Date: Fri, 25 Aug 1995 15:32:29 -0500
Subject: A/C Retrofitting

As an employee of one the world's largest automotive temperature control manufacturers/distributors, I work with a number of the fine individuals who wrote the Society of Automotive Engineers' (SAE) retrofit specifications. I am also a 1994 325is owner and BMWCCA member. Previously, I owned a 1984 325e purchased new. I read in _Roundel_ with interest and dismay various articles about retrofitting and HFC134a (i.e. R134a, Imperial Chemical Klea(r)): dismay because these articles have not been completely factual. Hopefully, my input will benefit BMWCCA members.

The June 1994 issue of _Roundel_ includes an article by Ice, Inc. This article claims HFC134a is the only refrigerant approved by the EPA. This was and is not the case. The EPA has approved for use in vehicle air conditioning systems HFC134a, DuPont Suva(r) and Intermagnetics FrigiC. Yet, the automakers have only approved the use of HFC134a in their respective systems.

A May 1994 "Technical Correspondence" column contributor recommended awaiting the market release of FrigiC, a proposed "drop-in" refrigerant. While FrigiC was recently approved by the EPA under the "SNAP" (significant new alternative policy) program, again it is NOT currently approved by any vehicle manufacturer for use in its vehicles. FrigiC does not meet SAE's specifications and guidelines for use in mobile air conditioning systems. Furthermore,it is unlikely service facilities will work on vehicles serviced with FrigiC.

Regarding retrofit, it is the recommendation of the temperature control industry, including vehicle manufacturers, component manufacturers, trade associations and the EPA to service vehicles with CFC12 (i.e. R12, DuPont Freon(r)) for as long as CFC12 is available in the market. When retrofitting, you may have to replace components that you would not otherwise have to replace when servicing your CFC12-based air conditioning system. By waiting, you benefit from a growing body of temperature control industry retrofit- and HFC134a-related knowledge.

Keep in mind a retrofit should ONLY be undertaken if you have experienced a major system failure and ONLY in consultation with your service technician. Depending on the failure mode, it is possible the cost of the retrofit procedure performed at the time of the repair will cost only marginally more than the repair itself.

My 325e was retrofitted as part of a fleet test. I experienced no system failure and no system performance degradation. In fact, performance improved as a result of first flushing the system with CFC12 and then evacuating the system for 45 minutes. BMWs are particularly difficult (read costly) to retrofit because the original equipment compressor BMW sourced from its supplier contains an elastomer (i.e. rubber) compound that disintegrates when coming in contact with HFC134a and HFC134a-system lubricants. The original equipment compressor is a rotary vane design manufactured by Diesel Kiki-Zexel for Robert Bosch for Behr. It was applied to nearly every model from the early 1980s through 1991.

BMW AG responded to this challenge by developing model-specific retrofit kits that include new specially-designed Seiko Seiki compressors. These kits are not inexpensive. For those who want to avoid this expense, you may have at least two other options: 1) purchase a new or remanufactured Sanden SD5 or Diesel Kiki-Zexel DKS model containing neoprene or HNBR elastomers (this will also require the appropriate replacement mounting bracket) or 2) purchase in the aftermarket a remanufactured original equipment BMW compressor containing neoprene elastomers.

Per BMW's retrofit kit specification, PAG (poly alkalyne glycol) lubricant is used in the new system. You may elect to use polyol ester lubricant if you chose the other two options. While polyol ester is the lubricant used with no problem in my 325e retrofit, the SAE specification does NOT specify the use of polyol ester, as noted in the Ice article.

Discuss with your service technician these lubricant options, as well as other retrofitting issues. Your service facility should be at least a member of the Mobile Air Conditioning Society or International Mobile Air Conditioning Association. Members of these associations are most familiar with retrofit procedures, SAE specifications and OEM service announcements.

Finally, in response to the article in the July 1995 "Technical Correspondence" column, industry-wide fleet test results seem to indicate chlorine deposits left in retrofitted systems added lubricity to internal surfaces thereby improving system performance. Chlorination on the metal and elastomer surfaces was NOT seen as a contaminant in systems retrofitted to SAE specifications.

Date: Fri, 14 Jun 1996 01:33:45 -0500

In issue 718, Monty Sidhu <> asked what he should do about replacing his defective compressor. This is a no-brainer: buy the Sanden conversion kit and mount a R134a-compatible Sanden SD508 (an R134a-compatible Diesel Kiki-Zexel DKS15 CH will work, as well). Sanden is an OEM for Chrysler, Renault, VW, Seat. Sanden is the Honda of the compressor market: it does not have significant market share in Japan, but it is a good compressor that sells very well in the rest of the world. Diesel-Kiki is an OEM for Nissan and Saturn.

New and most remanufactured Bosch units are NOT, repeat NOT compatible with the PAG lubricant used with R134a. BTW, what company remanufactured the Bosch you were quoted?

Hope this helps.

Malcolm Davidow
eAuto (sm): everything automotive (sm)

4.6: Tires
4.6.1: Snow tires
(by Richard Welty:

Nokia makes 3 tires worth considering:

Hakkapolitta NR09 -- a older tire, excellent in snow but noisy Hakkapolitta NR10 (or just Hakkapolitta 10)

  • newer design, excellent in snow, slightly quieter

    not available in certain sizes (but the NR09 generally is available in these sizes, which are usually narrower tires for older european cars.) Nokia NRW -- "all season"; not as agressive as the NR09 or 10,

    and reportedly more pleasant on dry pavement. far better than most tires labeled "all season" from what i hear.

by mail order:

Greer Enterprises in WI 414-747-0996

Pat Greer seems like a very nice guy and his prices are quite good. i paid $77/tire including shipping for a pair of 185/65R14s and $73/tire including shipping for a set of 185/65R15s back in December.

From: Timo Karttaavi <> Date: Mon, 24 Oct 94 11:44:54 EET

Someone asked about experiences with Nokia NRW and Hakkapeliitta. Maybe I can give my $0.2 to the annual winter tire discussion since I live in a country where winter tires are mandatory dec-mar and where Nokia tires come from (Finland).

First a distinction should be made with studded and non-studded tires. Here over 90% of passenger cars use studded tires but non-studded ones are constantly gaining in popularity because of advancing tire technology, recent warm winters and ecological view points (road surface wear is a big issue). Hakkapeliitta is designed to be used with studs and NRW without. In general if a stud-tire is used without the spikes it is worse in all conditions than a tire that is designed to be be used without them.

Comparative tests for winter tires a made annually by several nordic car magazines. They are probably the only ones to test extensively also studded tires. Nokia's Hakkapeliitta has always been one of the best in this category. This year the winner seems to be someone else, though (Gislaved?). Things like tire size and everyones differing priorities in certain tire qualities leave, of course, room for interpretations. Non-studded tires are tested also in central Europe but in Germany, for example, dry and rain performance are emphasized more over snow and ice. Last year the top three non-studded winter tires seemed to be Bridgestone Blizzak, Goodyear UG-4 and Nokia NRW.

Timo, '92 325i (with Goodyear UG-4 185/65-15 in winter)

From: Timo Karttaavi <> Date: Wed, 26 Oct 94 10:37:40 EET

> That was good info, thanks a lot. One question. You say the NRWs > rank among the top non-stud tires, but if I understand what you say, > that testing is done in Germany, where snow performance isn't > emphasized as much. Do you have a feeling for how good the NRWs are > in snow performance? How much do you give up compared to a serious > snow tire like the Hakkapelitta (with studs)? I just wanted to point out that there may be some differences in the test results from different countries. The German magazines have to take into account High-speed autobahn driving and the fact that at sea level snow is more of an exception than the rule. Nonstud tires are also tested in the nordic countries (Norway, Sweden, Finland). My information was based mainly on these tests. Sorry about the confusion.

In snow, slush, mud etc. there is not much difference between a studded and a non-studded tire. The best non-studs are certainly better than some studs. On ice, however, it begins to show. Even then if there is some roughness in the surface the non-studs grip surprisingly well, but if it is polished (e.g. by other cars braking at the same point) the difference is bigger. In the worst cases braking distance may double (it's still better than with summer tires). On dry pavement the difference is also significant. The studs degrade the grip and make a lot of noise. Some people consider this also a safety factor since the studs help to even up the worst and best grip in varying conditions.

So, there is mainly a trade-off between dry-road comfort and ice grip.


From: Timo Karttaavi <> Date: Thu, 27 Oct 94 14:05:15 EET

> I follow your discussion of studs vs non-studs, but I was more > interested if you had seen any comparisons of the Hakka.. vs the NRW? > Those tires are relatively rare in this country, so I havn't been able > to find any good information about them.

The problem is, that studs are normally tested separately from nonstuds. However, in recent years there has been some comparisons between generic stud and non-stud performance. I'm not sure if they involved specifically Hakkapeliitta and NRW. In any case the point is, that these tires represent the top performers in their respective segments and the difference between different brands is insignificant compared to the difference between a studded and a nonstudded tire. I get back to you if I run into one of these tests.

BTW I checked a recent stud test and the top two were Gislaved Nord-frost (Swedish) and Nokia Hakkapeliitta 10. Brands like Pirelli, Goodyear and Michelin were left somewhat behind.


(by Gordon

Hakkapeliitta 10's vs NRW's

On ice and hardpack, unstudded 10's and NRW's have comparable traction.

Hak 10's have a more aggressive, open, directional tread and have a clear advantage in deeper smow. They have 1/32" or more of tread when new, a single-ply sidewall and are *fully studdable* (and awesome -- nothing has more traction in my opinion.) Generally they are T-rated at 118mph sustained. They are unofficially rated at 40K mi treadlife. According to Pat, all ice racers in Wisconsin who are serious use them. (The Rocky Mountain Chapter Ice Gymkhana winner has run studded 10's for the past 5-6 years.)

The NRW's are not studdable and are unofficially rated at 50K miles. They run $10-15 more per tire. They run a bit quieter (although the 10's are certainly acceptable, in my opnion). The NRW's have a two-ply sidewall and are more stable and responsive in cornering. (I find the 60-series 10's to be more than adequate -- not like my summer D40M2's, of course, but still very good.) They are generally H rated (130mph) although some of the 65 and 70 series carry a T rating.

Nokia (Finland) makes a NRS-T with the NRW's tread pattern but with extra rows in the tread for studs, but this tire is not generally availble in smaller BMW sizes.

A personal experience with back-to-back comparison beween *studded* 10's and Blizzacks on the lake at Georgetown, CO -- the Bridgestones are very impressive in straight line performance, considering they are not studded. However they generate very noticeably *less* lateral cornering force than the studded 10's. I understand, also, that the tread life on the Bridgestones is pretty short and after the soft top layer wears away, one is left with a mediocre all-season.

4.7: Miscellaneous
4.7.1: Long-term car storage
  1. (by Rick Kjeldsen:

Based on my experience on storing bikes and cars for winter, I would:

  • Change the oil.
  • Change the brake fluid.
  • If it is old, change the antifreeze.
  • If you want be fanatical, change the transmission fluid and rear end oil, but I think this is less important.
  • Empty the gas tank, and run the engine dry of gas; Or put stabilizing compound in the gas and run the car till you are sure it is in the injectors.
  • Remove the plugs and squirt a little medium weight oil into each cylinder. Turn over the engine over a few times without starting it to spread the oil. Re-install the plugs.
  • Put the car on jack stands to get the weight off the tires, so they won't get flat spots.
  • Take the battery completely out.
  • Put mothballs in key points in the car (under the hood, inside, behind the heater grills, etc) to help keep out mice.
  • Plug the tail pipe suffeciently to keep out mice and moisture.
  • Keep the car in a dry place, out of the sun. At the very least, cover it with a thick, breathable cover. Best is to keep it in a dry garage. Either way, make sure the car can breath, so condensation doesn't build up. You may want to keep the windows open a little.

4.7.2: Limited Slip Diff additive
From: Jim Shank <>
Date: Sat, 19 Nov 94 21:06:31 -0500

I had been running Red Line synthetic 75W90 in my 1988 325is limited slip differential for about a year. The Red Line blurb claims that it works great in limited slip diffs, but recently I began hearing the tell-tale moan of the lsd clutch disks. So I changed to Castrol Hypoy C 80W90 (gl5) and on the advice of the net added a bottle of GM limited (gl5) and on the advice of the net added a bottle of GM limited slip additive. The noise disappeared immediately! After doing this, I reread the Red Line blurb and it does say that you can put the additive in the synthetic--I had just assumed it was incompatible with synthetic.They do claim that the additive is unneccesary, though. Has anyone had this problem with synthetic? Anyone use the synthetic with the additive? I think I'll try that combo when I change the oil before the first track day next spring.

By the way, the GM stuff is part number 1052358--a 4oz bottle cost $6.00--I got it at a Chevy dealer.

  • --Jim

4.7.3: Service Indicator Light Algorithm
How SERVICE INTERVAL INDICATORS decide when to turn ln a light. In case your wondering, according a service bulletin I came across in the late eighties, engine wear miles are counted according to the following: There are three temperature points used to determine a cold, warm, and hot engine. I think below 50C, 50-70C, and above 70C. Below 4000 rpm; for each cold mile, three are counted. Two for each warm, and one for each hot. Above 4000 rpm, one or two miles are added to the count. (not sure exactly anymore). When a total of 1800 ngine wear miles are counted, one additional light is lit. Thus you could go over 10000 miles before the first yellow light comes on.
4.7.4: Dual Mass Flywheels
Date: Wed, 12 Jun 96 20:29 EDT

Duel Mass flywheels are pretty common on later MY standard transmission BMW's.

It is on the 1.9l engine. also on the 2.8L as well.

(ED NOTE: An earlier version of the dual mass flywheel was also on the late 80s ETA cars)

The duel mass flywheel, is as the name suggests "Duel Mass". There are two parts to it, the primary mass (1) is connected to the crankshaft and the secondary mass (2) is where the pressure plate and fricton plate are mounted. The 2 parts of the flywheel are joined, the secondary mass mounted onto the primary mass on a single row bearing. The outer part (2) is movable (rotation wise) when the crank and inner part (1) are held still. Now it just does not 'flop' around, the movement is damped by an interconnected two stage spring system and some very thick damping fluid (special temperature resistant grease) (this depends on the manufacturer of the flywheel, there are different versions of damping) the grease is carried into the outer cavity between the flywheels and is distrbuted by centrifugal force. The reason for this setup is that cylinder pulses (rotational oscillations from varying load cycles) from the engine sometimes cause the gears in the trans to rattle or cause "drumming" in the body, the flywheel effectively eliminates those types of effects. The use of thinner oil in the trans is also a benefit for better shift characteristics, the use of thinner oil is only possible with the Duel mass flywheel. (well I guess you could use a thinner oil without a DMF but I would bet that the geartrain would rattle like an SOB). There is one more benefit and that is the DMF removes most of the torsional damping from the clutch pressure plate which then has less moments of inertia acting on it which will improve shifting effort.

The DMF is not servicable but like any moving part, they do wear out (mostly the internal springs) Before anybody asks what the life span is, sorry I broke my "Crystal Ball" yesterday (Damn!) now your ( the global"your") guess is as good as mine.



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