Yeah, the group IV PAOs are probably the way to go at this time. I run 0W-40 Mobil 1 in the C43 and 5W-30 Syntec in my wife's 325i for warranty reasons. Eventually I'll put Mobil 1 in the 325.

However, I suspect the III and IV base oils are pretty close in performance. I think the real benefits are in the additive packages, and in how much money a formulating company is willing to spend on testing.

If Chevron upgraded their Supreme motor oils to a Group III base oil (I think they are currently a II or II+) at the same price or slightly higher they would have a goldmine.

__________________
Dan
1998 C43