I did a drain and refill on my 2011, Big change in performance, smoother gear change and shuddering gone. Even fuel economy improved, will do second one in January to get some of the gunk that was in the torque converter out. So far I'm very pleased after the the first drain and refillFigured I'd update this. Did the drain and refill a few weeks ago. While doing it I noticed the front brakes were pretty bad so decided to do them at the same time. After the first re-fill took the E to get new pads/rotors and took the long way home. Drove it pretty hard to redline through the first couple gears to get it mixed up well and since I was still filthy and didn't feel like doing this job again in a week I decided to just do the 2nd drain and fill immediately. After about a week the occasional clunk I'd get on the very first cold shift from 2nd to 3rd is gone. Didn't really see any other differences but I also wasn't experiencing any other issues. Fluid was pretty brown on the first drain but didn't smell burnt or anything. 2nd drain had pretty good color so I'm confident what's in there now is mostly new fluid.