I know GM says the 4t45e is a sealed trans and the fluid doesn't need to be changed til like 100k, but is this true? My brother has a BMW with a 'sealed trans' and a BMW once told me that it was all bs and that he should flush the fluid every like 30k to be safe, "better $100 now then $5000 later."

I'm at like 60,000 miles now.. should I do the trans fluid?

 

I would change ATF and filter every 30,000 REGARDLESS of what anyone says.

Better to know its clean in there, than to be dealing with sticky valves and solenoids down the road.

Ask me how I know.