I'm just down the road from you. I typically buy my oil from the dealer (Brian Jessel) because the price is competitive. When I have needed oil and didn't want to drive to the dealer, I have used Castrol 5w-30 from Lordco. About the same price. Lordco also sold the Castrol 'European Formula' when I looked, but I wouldn't pay any more for it. I would happily use Mobil 1 as well.

I just don't see any merit in the whole group 3/group 4 debate. They are both full synthetics (but watch out for Castrol Blend, that is not a full synthetic at Lordco). What is important to me is that they are 5w-30, and have an API SM rating. I don't pay any attention to the BMW LL standards, since they are so out of date and since BMW recommended not to use LL-04 in North America in gasoline engines due to shortened oil life. LL-98 and LL-01 are so old I think they are irrelevant.

Using quality oils and OE filters as above, my vehicles run great at the recommended oil change interval. If it gets much over 20,000 km on the lights I tend to do it early because of the elapsed time, I don't put a lot of km on them. My service lights are aiming for around 26,000 km these days, between the two cars.

Jeff

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue