I'm thinking about having the Chevy dealership do a complete flush and fill on my auto tranny. Replacing the entire 7 or 8 quarts of fluid after a chemical flush. Cost about $180. I've heard two schools of thought on this. The most prevalent is that if it ain't broke don't fix it and that stirring up all the stuff in the tranny would be a bad thing. The other is it's a prudent maintenance item. The vehicle is a 1999 4WD Blazer with the 4L60E tranny with 85M miles on it. As far as I can discern there's been no tranny maintenance ever done and I'm not experienceing any problems. Any comments/suggestions??

 

85K, 99.
Flushing should be fine, although I think it would be better to drop the pan, install a drain plug, and top off with new fluid (4-5 quarts). Then once every year, drain the pan, and top off with new fluid. No other maintenance is needed.

If you tow, drive in the mountains, or do lots of stop and go driving, adding an auxiliary tranny cooler is a good idea.
Heat is the number one killer of transmissions.

 

Install another aux cooler. [8D]