BMW Repair: oil, synthetic 5w, lease vehicle

Question
Just purchased 2007 530i and am confused about oil and change interval.  Most I read indicates not to use BMW suggestion of 15000 miles.  Should I change at 7500 or other milage?  Also I plan to use synthetic MObil 1 10W-30.  Is this o.k? or should I use another grade and brand?

Many thanks

Answer
John, when I change the oil BMW at the 15k interval as part of an oil service the oil comes out very dark. If this is your car and not a lease vehicle then I would suggest you change the oil and filter at 7500miles instead of 15k. There is nothing wrong with changing your oil and filter at the recommended intervals. If you care more about your vehicle than the average person and want it to last then you might consider changing the oil and filter early. BMW uses Castrol full synthetic 5w-30 motor oil (7 quarts for your engine). Please use this oil. Use BMW oil filter kit part number  11 42 7 566 327 (should be about $11). I believe our dealer only charges 0.5hrs for an oil and filter change. Check the oil level in the I-drive (instruction should be in your owners manual).
-Evan