Hello all! I have an 01 Ford Ranger (see signature) with 145k on the clock that I am getting ready to take on a 10 hour road trip (Louisville KY to Destin FL). I flushed the transmission at 30k and 60k with Motorcraft Mercon V, and flushed using Mobil 1 ATF at 90k. The question is should I flush again since the current fill has roughly 55k on it? I wonder how long the M1 ATF is good. The guy at the transmission shop said he wouldn't flush until the fluid has at least 75k on it. What would you guys do?