change fluid auto tranny
I have not done the auto tranny in the new 3 series but in general and in other bmws you need more to change the fluid. Most don't have a drain plug and even if they did you should change the filter in the tranny when changing the fluid. So first the bottom of the tranny is removed, and yes fluid comes pouring out. If you drop one corner first (loosen all bolts then pry a corner down it makes getting the fluid out easier then remove the bottom pan. If you got the filter before hand you'll figure out how to change - usually two bolts hold them on. Clean the pan, put the new filter on, put the gasket on the pan with your favorite glue and reattach. It is important not to over tighten the pan bolts as they strip easy. Then fill. Most bmw's don't have dipsticks so fill till comes out fill hole. If possible I'd recheck a few days later and make sure level was correct. Auto trannies should have fluid changed more often then manuals as they run hotter and have pressure plates (similiar to a clutch) that engage and disengage. These wear and the wear products plug the filters up. This lowers the pressure in the tranny and they run even hotter and slip more and thus more wear. I'd never let an auto tranny go moe the 30,0000 miles without changing fluid and filter.