changing fluid

changing fluid in a high milage trans is good or bad. i have a suburan with 170,000 miles and shift find but fluid is getting dirt. have had the fluid changed once thru the cooler lines at the dealer around 80,000 ago. was thinking about changing fluid and filter this time but here negative on changing high milage fluid. dont know if these are trans with problem already and trying to fix with a fluid change

Change the fluid. Old myth about not changing.