Ok so maybe it's not 100% new... I got the transmission from a friend who bought it from GM performance parts to go into his Chevelle. When he installed it in the car it ran fine but it leaked ATF out of the vent tube. His installer got a new transmission under warranty from GM and did not have to return the old one so he gave it to me. I was hoping that he just overfilled it so I installed it in my 06 awd. Needless to say I am now experiencing the same problem, I talked to a couple of GM mechanics who hadn't experienced the problem before. I used HP tuners to check the temperature while driving on the transmission and it stayed about 185° until I stopped or slowed down then it climbed quickly to over 205° on the little stretch of driveway leading back to my house and used a few quarts of atf on roughly a 20 mile drive of very light driving, never going over 2500 rpm, if I gassed it atf would dump out quickly. I am wondering if it could be a pump problem? At first I thought it could be a clogged cooler line but the problem went away on my friends car with a new transmission. Sorry for the long winded post I just wanted to be thorough, if anyone has any thoughts I'll give em a whirl, thanks!