Hello everyone. I have a 1998 Ford F-150 v6 with an automatic transmission and undetermined mileage. The gauge cluster was switched out years ago including the odometer. It’s most likely in the 80,000-90,000 mile range just guesstimating. But it could be as much as 100,000. The transmission fluid has never been changed to my knowledge. The fluid doesn’t look horrible and the transmission seems to be functioning ok. It can be a little slow to go from second to third every now and again but that’s the worst of it. No slipping or anything like that. My question is, would it be safe to do a fluid change at this point? I would like to preserve the transmission as long as I can and I know that these f150 trannies can be a little finicky, so I would like to hear some opinions before I proceed. Thank you for your input!
I would change the fluid and filter but I would keep the old dirty fluid just in case if it did start slipping I would then empty it out and put the old fluid back in
My 98' with the 4r70w tranny was sitting for a lot of years, although it only has 58k miles on it. The nice thing about those is, they have a drain bolt on the torque converter as well, so you can dump out the torque converter, and drop the trans fluid pan, switch out the filter and fill that too if you want. If you do, you will change out about 12 of the 14 quarts of tranny fluid. I used the valvoline max life atf and it smoothed out that rough shift from 1st to 2nd a bit, but I am going to switch out another 10 quarts of amsoil this weekend.
I can't promise anything, but I have never had issues doing a non power flush trans fluid change. Like Scotty said, be safe and keep the old fluid.
