Re: What Oil DO NOT use? (archive)

: well, it was a long post. To make my answer short :
1. Do not mix synthetic and regular oil. NEVER ! They are different chemicals and do not mix well.
2. If your car gets older but the tempeture outside gets lower, you still need the 10W40 oil, or some case the 5W50. I wouldn't use synthetic oil in old engine (over a 100k or even more on the BMW V12) because the synthetic oil is more slippery and it could leak a lot easier at the gaskets, seals. If you have no trouble using it then just use it ! The synthetic oil doesn't burn that fast and doesn't freeze that easily.
3. Most modern car (all of them) needs the multi grade oil which is exactly what oil makers sells. If you are in a single climate are (Florida) you might be able to use single rate oil like W30 but what is the advantage ? The multi oils are so good, you have no need to use anyhting else ! Besides the synthetic oil always multi-grade.
4. I use Mobil1 15W50 for several reasons. I live in Florida where the heat is a problem and cold wheather isn't. If i'd be up north, I'd use a 5W-50 or a 10W-40 but synth. oil only. I like them, and I trust them ! Castrol also good, I had bad experience with them, so I switched to Mobil1.
There is always a factory oil - I know expensive and probably a same as any other brand.
That's it for today ! But I also would like to knwo what other people use.
Oil filter = factory for several reason
1. Good quality comes with O-ring
2. Cheaper than aftermarket
3. The dealer have them in stock, and the aftermarket always a special order.
But I got the 840Ci and my oil filter is only an insert. I don't know the 850 , never had one (yet)(

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