I've got an '08 G8 GT with just over 20,000 miles on the clock, and I've been having issues with my trans since I bought her at 153 miles. I've had it to the dealer at least 6 times, if not several more, for the same issue, but they claim they can't find the problem. They performed a service bulletin for some seals in regards to a flare shift, but that didn't fix it. I even had to convince them there was a bulletin in regards to the flare shift... They also claimed to have updated the computer (or at least checked it) on just about every visit.
The extent of my problem:
Harsh shift from 1-2
Flare shift from 2-3
These only happen when the trans is cool. It is best noticed in Sport Mode, but it can happen in regular drive mode. I have noticed oddities if I use manual select, too.
I'm taking it back to the dealer on Monday to let it sit for 5-6 hours, then come back and take it for a short spin while she's cooled off.
I'm kinda pissed because even after getting the owner of the rather large dealership involved, they still can't seem to help me. They've done other service work on my car just fine, so I'm slightly hesitant to find another GM dealer.... but that's why I seek out someone here who may know, or works at a dealer as a mechanic and wouldn't mind checking out a fellow member's car.
Your help is appreciated!
-Brian