Cary : thanks for the wirte up!
I contacted BMW customer relations and asked what oils besides the factory brand are acceptable for use. Keep in mind I have a 2000 328i.
The answer: "Castrol Synthetic, Mobil 1
>Synthetic, and Valvoline High Performance Synthetic with a weight of SAE
>5W-30 are also approved by BMW, however, these oils are not formulated for
>15,000 miles between oil changes like the BMW High Performance Synthetic
>engine oil. "
But he recommended the BMW synthetic as best choice.
I take my car in for all the services as per the computer, every 15k miles and get oil service, where I get BMW oil, but I do my own home oil change in between, at 7500 mi, where I put 5W30 Mobil 1. oops! My car got 5W30 2 times so far, but in the future I am switching to 0W40!!!
Weird thing though, I went to the oil application page on the mobil1 site and they suggested 0w-20, 10w-30, and 0w-40 as being okay.