This article is nothing but…
This article is nothing but GM propaganda. As a Sierra owner since 2016 I can tell you for certain that flush doesn’t do anything. I’ve had 3, multiple fluid changes, multiple relearn (which by the way the good people at GM tried to convince me for more than 2 years that it is a smart trans just learning how I drive) and none of that crap did anything. They refused to replace the trans and it has devalued the resale of my truck. Just imagine a test drive with a prospective buyer when the transmission shifts so hard it feels like we’ve been hit by another vehicle.