From Murfreessboro-2002 Sierra 1500 with 5.3l, 202,000 miles, automatic transmission. Never changed tranny fluid and have no issues with it. Should I consider adding an additive as a preventative measure? Love your shows/videos!
As the old saying goes, if it ain't broke, don't fix it. I wouldn't mess with a GM transmission after all those miles if it was never touched before. We also don't know the compatibility of the additives in question and the transmission. It's generally a very bad idea to put fluid in there that isn't made exactly to the original fluid specification.
You'd need to remove the same amount of fluid that you're adding to put the additive in without causing an overfill situation. Also, by messing with the old fluid and removing some of it, you could create a problem, like slipping, where one didn't exist before.
