My BMW shop recommends 7500 miles. Reason; per their tech is that the BMW oil filters break down (they are paper) and basically disintegrate at that point. I really am not a fan of having my oil filter release all that it has filtered back into the system. This independent BMW shop has been in business for 20 plus years and they have a stellar reputation here; so I put a lot of faith in that advice. Therefore I do the 7500 intervals and we did that with our 2000 323i and it was in fine shape at 98,000 miles when we sold it a month ago. My .02 cents.