My wife has a 2005 Explorer V-8 with the 5 speed auto tranny. She bought it new, it now has around 165,000 on it. I have had the tranny fluid completely exchanged and new filter approximately every 30,000 miles, except for this last time because the shop said the fluid and pan is so clean that they just did a drain and fill with a filter change. It shifts like when it was new. The indie shop drops the pan, cleans it, changes the filter, refills then does a complete exchange of all the ATF.
Whimsey