Re: 2008 gmc sierra transmission fluid change
I used to work at Snappy-Lube & they suggest it be changed every 50k.
I don't work there anymore, but all that aside, they do have a really good tranny flush system. It's based on the radiator purge/fill service.
Unlike most places that pull the tranny pan which only drains whats inside the tranny itself, leaving old fluid still in the converter, lines & cooler. Their system purges the entire transmission, torque converter, lines, & oil cooler. IMO it's the best, if not the only way to get all the fluid changed.