Love these oil threads!
No car mntce. issue is debated with greater frequency or fervor than oil changes. Full Disclosure: I'm a daily visitor to a Porsche forum...things can get pretty ugly there.
>Change oil + filter every 5K miles or annually, whichever comes first.
>Use a top quality synthetic, and don't move up to a heavier weight oil unless you live in a hot climate or track your car.
Our BMW engines, like those of other German luxury brands, are very complex (too complex?). Skimping on oil changes is a false economy for long term owners.