The 8-sp is a pita for the first 10,000 miles of driving. IMO the problems are the voodoo GM computer programming.
There is another problem looming with the 8-sp; “Shake and shudder on Acceleration Excessive Engine RPM Fluctuation – (Jan 20, 2016)”, all 2015-2016 with 8-sp transmission.
Temp solution, double flush the trans, R & R the filter. If problem is not resolved the problem in internal to the torque converted and new one will be available soon.
If you are driving along between 30 and 65 mph and the vehicle shakes or shudders below 1600 rpms, you have this problem and it will not cure itself. The feeling is like driving over rumble strips on the road. ,
They were supposed to do the double flush, R&R the filter last Thursday on my truck. Has appointment and was talking with someone in the showroom when the SA came up and said, we cannot do it today. The parts dept does not have enough Dexron-HP in stock (only 5 qts) and they called around to 3 other dealers in the area and between them they could only come up with 13 qts of trans fluid, they figure 30 to do the job is adequate. Unbelievable!
Service Bulletin is PIP5337A
btw – I have a 2015 Sierra Denali 6.2L CC standard box 4wd.
