Unofficialbmw.com

[Z3DOM]

Recently purchased an '02 Z3 2.5i from a GM dealer. According to the sticker, someone changed the oil recently but there is no indication of what type of oil they used. My Bentley manual says to use synthetic.

If synthetic was not used in the oil change can I just go ahead and put synthetic in when I change oil & filter? Can synthetic and regular oil be mixed a little bit? Any recommendations on oil?

Thanks
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LUANDA02

[donaldan]

Mixing synthetic with petroleum based oil is perfectly OK. I regularly use Mobil 1 15W50 on my 2 BMW's. As long as you change the engine oil regularly and live in temperate climate, type and grade of oil to use makes very little difference.
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Don

[Bagger]

[donaldan]

"Change it when the lights indicate"

I like to baby my engine. Three thousand mile interval is what I follow even with synthetics. The 7k to 10k interval indicated by the lights is way too long for me. I won't go over 5k interval. That way, you give little chance for sludge to form and your engine will love it.
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Don

[Bagger]

Yes, Don ... You can change the oil every week if you like. But, the point of using synthetics is 'extended use'. My Porsches require oil changes at 16,000 miles. That's what the manual says. That's what the dealer says.

But, who am I to go in the face of the manufacturer?

Synthetics reduce friction a good deal, extend the service interval, but their real fame lies in their ability to reduce moisture accumulation in the solution compared with dino oils.

If you change your synthetic oil/filter at 3K you are wasting your money. Sludge build up? I think you are mistaken, Don.

Corvette, MB, Porsche, BMW and others all come from the factory with synthetic oil installed. They also provide manuals stating what the service intervals should be. In BMWs case, they even have these neat little lights that count down to service time for those of us that can't quite figure it out on our own. All of the above manufacturers have service intervals of ~10-16K.

But, if you wanna change your oil at 3k. Hey, be my guest. There really are no rules. And, I don't wanna get in to a pissing contest as to when to change oil and what oil to use. That's just stupid.

[donaldan]

Touché !
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Don

[Bagger]

[6doublefive321]

My $.02. My 3.0 tells me it needs a change between 12 and 15k. I change it at 10k. If you want to religiously do 3k services, save a lot of money and use dino oils. Synthetics are so much better in regards to impurities, they require less freqeunt changes.

I agree with the rest. Do what makes you feel good.