In Reply to: Re: Bob, are you sure **/30w oil is adequate for posted by Bob ///M3 on September 12, 2000 at 13:36:09:
Regarding the other gentleman's comments about 5W40 am 10W50. There is more to be lost than gained with these oils. First, I believe these are Syntec blends which, in the US, aren't even in true PAO synthetics. They are better than most petros but they are in a completely different clasification of base oil than Amsoil and Mobil. Second, any oil that has a viscosity spread of more than 30 points is using a viscosity modifier to get the extra spread. The VM breaks down faster than the base oil (particularly in track conitions) and eventually causes the oil to behave like a straight 25 or 30 wt oil. The cold start beneifit you originally bought the oil for is essentially gone by the time your drain interval is reached. In this scenario the 0W30 is better for your car per Bob's argument.
The point is, if you are using your car on the track, use the best like Bob does.