chefwong, regarding BMW/Castrol 5W-30 versus Castrol SLX 0W-30:
SLX is probably better over longer intervals (but we don't have many UOAs on this stuff yet), however, if you're changing at 5,000 to 7,500 mile intervals, either one will be just fine. Plus there's the convenience factor of the BMW/Castrol 5W-30 if you'll be using the dealer for service. Might be worth the trip out to Huntington every so often, since they'd give you a free BMW loaner car to use for the day!
When you call around the various dealers, be aware that some price an intermediate oil
change (service indicator is not reset) cheaper than an oil
service (service indicator is reset, and other checks are done).
Since you have some leftover Redline, you might as well use it! And you got it for a decent price... out by me it's way overpriced, around $8 per quart.
I really do like Redline's MTL (I used it in a '94 Civic), and their D4 ATF is supposed to be very good in the E46 3-series manual gearbox.
Redline's water wetter and their fuel injector cleaner is said to be good stuff too.
pscholte, I thought MB is using M1 0W-40? Well at least the AMG models are...
rob-the-oil-nut, wow, that's something else! Plenty of people have achieved high mileage records without resorting to such extremes