Diesel onejust because the mileage gets worse with higher ethanol - while it is cheaper than pump gas it's not cheap enough
thanks for the comments guys, honestly I have taken a few 3'ers past 200k on rotella and never had engine issues, just a lot of leaks (but show me a bmw that doesnt leak oil). I don't think I will be switching this car off of it
my wifes n55 x3 gets the LL01 motul, so maybe I'll send that in soon to compare
