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From digest.v7.n606 Mon Nov 17 15:28:15 1997
From: Ray Vacha <>
Date: Mon, 17 Nov 1997 10:57:03 -0500
Subject: Mobil 1 Oil - The Great Escape Artist

Jacki Billings writes: <snip> Recently, I was talking with a mechanic who told me that he does not use Mobil 1 because its prone to cause engine leaks. Needless to say I was
taken aback as I use Mobil 1 religiously. Has anyone else heard this before?

Sorry for causing another "oil" dilemma.<snip>

Your mechanic is sorta correct. More accurately, Mobil 1 has a somewhat deserved reputation for causing engine leaks in leaky engines. This goes waaaay back to the unrefined dino juice days, the days before Mobil 1 and effective oil additives. In these days, it was very common for engines to develop gums/sludges on nearly every interior surface. The sludges actually helped those 'ol blocks in a way by sealing the engine, thereby preventing leaks! Then along comes Mobil 1. Mobil 1, by its very nature, is able to hold a lot of crap in "solution", much like water can hold a lot of sugar in solution (remember how much sugar you had to add to make rock candy?). That nature, BTW, is due to the absence of long really long hydrocarbon strings, I believe (experts - waddaya say?). Mobil 1 dissolved copious quantities of the sludge/stop leak goo with each oil change and sooner or later, many engines started leaking. Some people were left to believe that Mobil 1 had somehow "done" this - that Mobil 1 had caused things like gasket deterioration and worn valve guides - when in reality it had simply removed the stop-leak! Generally, the state of engine design has greatly advanced in recent years, and engines just aren't as inherently leaky as they used to be - tolerances are much tighter and gaskets are MUCH better than they used to be - remember the old 60s blocks that led you to believe the auto companies owned all the cork suppliers?

There is another truism widely held, even on this digest, that it is best to put your engine on a strict Mobil 1 diet early on in its life. Mobil 1 dissolves a lot of crap inside your engine (good) but this crap remains trapped in solution until your next oil change. As you might expect, engine wear protection is compromised with this stuff in solution (bad). Not a problem for a newbie engine, but a possible compromise in an old, sludged engine. Oils do a better job of holding stuff in solution at higher temperatures than at cold - this explains why valve head covers/rockers/springs were notorious sludge magnets. Take a look in there - if you see no sludge, switching to Mobil 1 should be no problem. If you do see sludge, consider adding a high detergent additive to your oil and change the oil _frequently_ until the sludge is gone, then change to Mobil 1 and be mentally prepared to fix a leak or two along the way if it is an older engine design.

P.S. For the factual purists out there, Mobil 1 _is_ dino juice. It works it magic by constructing hydrocarbon strings out of really small ones (a readily controlled process) while "dino juice" is deconstructed by taking the really long chains found in crude oil and "cracking" them to make (generally) smaller ones (not a very consistent process).

ATTENTION: Despite any other listing of product contents found hereon, the consumer is advised that, in actuality, this personal computer consists of 99.9999999999% empty space, occupied by nary a gluon or even a neutrino.

Ray Vacha
97 E39 540i 6 Speed "ZEIT" <-- On a "strict" Mobil 1 diet now BMW CCA #143366
Northern Ohio Chapter

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