X has 106,000 miles on the clock. Put RP ATF in the tranny at 60,000 miles. Now change in shifting or performance in 46,000 miles. No color change or burnt smell. Fluid looks the same today as the day I put it in. Plan to go another 15,000 miles on fluid then re-evaluate.

DSMMH

 

My truck has 74000 on it currently, bought it with 67000. I have no idea when the last trans flush was done, but the fluid still looks brand new. I think all these guys with the crazy intervals (some people are doing it every 15000) are the ones who tow really heavy and push the trans to its limit.