Jennifer Ott
Your service light will come on when it has been 6000 miles or a year since your last service, which ever comes first. There are 3 dealerships in Michigan. BMW Detroit in Rochester Hills service for your RT is $250 for the regular oil change and rear drive oil change. The larger service with both oil changes, plugs, air filter and valve check is $500. 248-402-4010. A regular annual is a little less than that, I think.
If you are closer to BMW Of Southeast Michigan or BMW Grand Rapids, you can call them for prices.