Being completely honest, I have no idea. I bought the truck used and had no idea what it had been through up to that point. I’m guessing I hadn’t done a fluid change myself, though I’d only had it for ~15k miles. Odd thing is that I absolutely don’t remember having any transmission trouble on that particular vehicle…guess my memory is failing with age!
I service mine anywhere from 25 to 30 thousand miles. Check the fluid every oil change though. Same problem. I get about 125k miles every time. Other than weak ass transmissions chevy is decent. I’m a big fan of the old 5.7 350 motors and the 396 and the 454. 472 cadi engine. It’s just this particular transmission that is terrible. Yes I know there’s a few out there that do well and get more than 125k miles but I’ve never personally owned one that does better than that. In my opinion after owning over 100 vehicles in my life the 4l60e is the worst transmission I’ve ever owned.