Lots of good information here, I like reading the Roundel's Mike Miller who points out that BMW lengthened their service intervals only after offering the free maintenance program. Pure Marketing. I change fluids according to the old schedule which for me in general is:
1. Oil: 1,250 mile break in then every 7,500 or once a year
2. Gear oil: Tranny and dif break in then every 30K or every other year.
3. Brake Fluid: once a year
4. Coolant: every other year, pint of Redline (RL) Water wetter.
5. Air filter/Cabin filter: once a year
6. Add RL S1 or Chevron Techron to fuel twice or so a year
7. Plugs: 30K miles.
I live at altitude, track my cars and live in a dry dusty enviroment, which is by definition "severe service", which I think supports a more conservative view of maintenance intervals.
It's all easy to do and fun anyway (except perhaps coolant) plus, it makes you feel all warm and fuzzy about your car.
Mike Miller likes Redline, I also like Redline and German Castrol Synthetic as well as the Euro formulation Mobile 1 Synthetic 0W-40. I like Redline or Royal Purple 100% Syn. gear oils.
Blackstone UOA results as well as others can be seen on the nerdish websites Bob is the Oil Guy or The Oil Drop. Can be helpful as some engines are harder on oil then others. For Example, there is about 20 guys on the board that have Audi RS4s and have fuel dilution problems and have come up with an additive fix or just change their oil every 3-5K miles. BMW engines consistently are mentioned as "easy on oil" in terms of shear and fuel dilution even with 15K mile changes. True also of the M-Motors. BMW's Castrol developed TWS Motorsport 10W-60 is also highly rated, so is the other BMW Synthetic Oils.
This new turbo motor could be different however, as it runs hot, is more highly stressed and also uses the newer direct fuel injection method (as does the RS4)....I have'nt checked UOA results on the N54 motor yet.
I've owned 8 Bimmers and none have had problems, used any oil ever and just purr. I guess that's why I keep buying them!!
Hope this helps.