SteelD6

The switch to the Amsoil Signature ATF was completed and the problems with the transmission are gone. Obviously too soon to tell about the durability of the fix, but so far I am pleased. Truck smoothly shifts through gears upon brisk acceleration from stop to 73 mph and also smoothly accelerates from 73 to 85 when passing.

I have a 2019 GMC AT4. Last year, at 63000 miles, my right side lifters failed. Totally covered by my extended warranty (Zurich) the dealership ended up replacing both right and left side lifters, pistons, cam shaft, etc. Previous to that, at 55000 miles, I was having the slipping from 1-2 and vibration at 53 mph and 1500 rpms. Dealer flushed/filled the transmission. Problem went away. Transmission problem reappeared at 70000 miles only the vibration was at 45 mph instead of 53. I had the transmission and torque converter flushed, filter replaced, and filled with AMSOIL SIGNATURE SERIES ATF HP. This was 2 weeks ago, problem is solved. The tech bulletin has the fix being Mobil 1 ATF HP.

I am going to use Amsoil Signature Series ATF

I have a 2019 AT4 with 5.3 V8 and the 8 speed transmission. Was having hesitation and surge at start up and rumble at 1500 rpms in the 52-57 mph range. Took the truck to the dealership and they did a flush and fill at 51k miles. Problem solved; I am now at 73k and the problem is back, though not as pronounced. I am switching over to Amsoil Signature ATF next Tuesday. I will keep this thread posted on how it goes/results. I have used Amsoil engine oil for decades but I am just an average guy with nothing tied to a brand. I will provide honest evaluation and feedback.

Interesting read on replacing the rotors, pads, and sensors on the AT4. I also have a 2019 AT4 and not afraid to admit I am a bit daunted by my pending task of replace all of the aforementioned. I have an onboard scanner...so will I be able to clear the error codes?