Our 07 X3 seems to be on an 18K mile service interval... The first service light went off at 18K and I'm on track to see it again at 36K but since it is coming up on its 2nd b-day it will be changed closer to 35K.

I change the oil every 5K miles on the vehicles I purchase and plan to keep but since the X3 is leased I'll let them maintain it how they want to. I don't see a problem with the 7,500K mile option either. 3K was the old non synthetic recommendation everyone has a different opinion. The engines and oils are significantly better these days so it boils down to whatever makes you comfortable.