hello all ..got a real puzzling question for tranny guys,,have a 93 dak 4x4 extenda cab 3.9 mag 175,000 miles ,,getting ready to change my tranny AGAIN!! and i'm wandering about the fluid i'm useing,,last tranny lasted 6 mo ,,it was a used tranny from a 318 and when i changed it ..dropped the pan and changed the filter and the replaced the fluid with valvoline atf+4 full synthetic tranny fluid(i've always used valvoline products and never had any issues with them ) ,, and there a(dodge licenced tranny fluid).. everybody said use atf+4,,well my question is this ,,my first tranny was the tranny that came original with the truck ..i beleive it was a 42 tranny,,and i had to change the filter in it ..and when i did i used atf+4 fluid because everybody said it was the best! that lasted about 3 months before the tranny started slipping and i then pulled that and replaced it with the bigger beffier 46rh i beleive ..outa a 93 318 dak and again put a new filter and filled with valvoline atf+4,,when i dropped the pan on the 46 before changing it the pan was clean..very minor sludge on the magnet about typical for the year and milage on the tranny,,well that was 6 months ago and about a month ago the tranny just stopped moving completly got it home and dropped the pan and the magnet was about 1/2 " thick in black sludge ,,changed the filter that was so dirty it looked like it was 10 years old and refilled with atf+4 again.. it seemed ok untill about a week ago and now it's starting to act up again ,,once it warms up it's getting slower and slower to engage to move,,no banging or clunking just isn't moving real fast ,,ok thats what i've done and where i'm at ,,i just picked up another 42 tranny and i'm about ready to change another one of these "fun trannys to change" and i'm wandering about the atf+4 fluid,,this and my first tranny are marked "use mopar ATF plus type 7176 auto trans fluid or dextronII" ,,it's not marked to use atf+4 so i'm wandering about the full synthetic fluid and if it's been causing the problems ..i deceided to pull the first tranny apart yesterday and check out how one of these work ..when i got to the clutches and plates out the clutches weren't really worn down they had what i would call pot holes in the disc surface ,,so i'm wandering if these trannys were designed more for a oil based fluid rather than a synthetic fluid and if the synthetic fluid may be causeing the disc wearout like it is ..i am going to be adding a tranny cooler this time because i've herd of the poor design with the tranny collers in the rad but it just seems odd that when i started useing the atf+4 fluid is when all my problems started ..and i sure don't enjoy changing trannys every 6 months..oh ..anybody want to buy some rebuildable trannys ..lol..lol..will have a 42 and a 46 for sale cheap,,u pick up..lol..
crazy

 

ATF4 didnt exist when these transmissions were manufactured. It was developed later and then was chosen as the "ideal" fluid for chrysler transmissions. As long as its a recommended fluid you should be fine. So if it says you can use cheap ol Dex II, and your having bad results with ATF4 then try dex II and see what happens.

 

Did you have cooler and lines power flushed after the first trans failed . When **** lets go it settles in the cooler to come back and kill again. I don't go for all the hype of synthetic but when it comes to trans fluid you can't beat it. It can live at a much higher temps than what would toast dextron .

 

+1 to what injmopar said. I have heard from a few different people that have gone through several transmissions in these trucks that it turned out being a problem with the cooler lines/cooler. I would suggest when you get your new transmission, that you flush the lines and run them to an aftermarket cooler and forget the factory one.