I recently purchased a 5.4 l F 150 automatic with 150,000 miles the transmission runs properly with no issues but I want to service the fluid and have heard about tranny slipping problems after putting in new fluid. So should I just replace the filter and put in all of the old fluid back or should I replace the filter and replace half of the fluid with new fluid and the rest the old fluid. I’m pretty sure the fluid has never been serviced so I was wondering which would be safer so I don’t start getting slipping issues.
That really depends on if it has been changed out before. I would take a look and see what the fluid looks like. If it is really black, I would just do a filter change out and keep the old fluid. But if it looks like it has been changed before, I would do a drain and fill....no flush...and replace the filter.
I'm curious about everyone saying "don't flush". My Nissan dealer only does flushing; drain and fill isn't an offering. But they say that the machine they use does it under the normal engine pressure and not forced. My independent Japanese shop does and says the same thing. What gives?
@s1c-em The only companies I’ve seen really push the flushing is Hyundai and Nissan. Although I’m sure there are others. As far as I know most of the domestics don’t really call for a flush and good thing cause my 15 f150s 6 speed has so many solenoids and other sensors a flush would likely do damage. I’ve never ever flushed a transmission. Just drain and fill/ filter, gasket. And I had a 92 f250 with original transmission hit 300k mi before it started slipping.
Yeah, I mean I always go with what the dealer recommends/offers. Our Hondas were drain and fill, but the Nissans are flush. My Japanese specialty shop is just flush and they work on everything Asian (really on anything, but still). I think it only becomes a problem if it's done under excessive pressure and/or the fluid is already very dirty and hasn't been changed in a long, long time which would increase the risk of forcing sludge into places it shouldn't be.
American cars, as they age, shed more clutch material into the fluid than Asian cars. For that reason, a low pressure flush is ok on Asian models. But with American cars, you are likely to cause damage due to all the debris that is in the fluid.
That's fascinating. One would think they would be on par with one another. Do domestic brands use inferior materials in their parts?
Indeed they do, unfortunately. Scotty has even mentioned this on multiple occasions.
Copy that! I know he's definitely not much of a domestic fan....LOL! I have long assumed this to be the case on my own but hadn't really ever considered how it may make the transmission flush riskier for a domestic over an import. Appreciate the insight!
Fordtechmuckaloco on YouTube. He has a video about that transmission and anything else Ford.
