I used the popular but simple turkey baster method - just extract as much fluid from the reservoir as you can using a turkey baster and refill with new ATF Dexron III fluid. After driving for a few miles and making a few lock to lock turns, repeat the process to extract more old fluid and refill with new. I did it 7 times and now I have about 90% new fluid.

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'11 xDrive40d M Sport - 4-zone climate - Active cruise control - top view - side view - massaging/heated/ventilated seats - Powered bootlid - Comfort Access - BMW Advanced loudspeaker system - Rear side windows sunblinds - Adaptive headlights - Soft close doors - comfort seats - DAB digital radio - Panoramic glass sunroof - folding mirrors - High beam assistant - Head up display - Speed limit display - Lane departure warning system - 7 Seats - Digital TV - Internter - apps - USB