what oil to use in t5 tranny?

[gijohn40]

ok the old CJ7 is getting a oil change in the tranny... according to the book it takes a special Jeep brand oil...

What has everyone else put in their T5 trannies? or should I go to the jeep stealership down the road and get that special oil?


Now I don't want to void my lifetime warranty on my tranny so set me straight! lol

 

[brokejeep]

I think it is ATF4 which I thought was wrong but I put 90w in mine a few years back and it blew. try cjoffroad.com

 

[Ken Olsen]

Pennsoil Sycromesh get AT the Zone

 

[gijohn40]

I tried cjoffroad.com and they are just as confused as anyone... I see people saying to use atf but then they say they blew their tranny a few months later... and then I see others say gl5 80-90 but then say that it eat their brass sycros months down the road.... seen a few say they used sycromeshmax and have been going good for years....

The most common thing I did read was to get rid of the t5 and get a t18!
And seeing my tranny needs to be rebuilt Im thinking this is a great Idea seeing that I am running 33" tires and have 456 gears in the axles... and thinking of going to 35" and changing the d300 to 4.1 gears.....

 

[Cherokeester]

According to Chilton's on page 1-34, you use Dexron II ATF for T-5 trannys out of CJ's 1983-1986.

 

[Rusted]

According to Chilton's on page 1-34, you use Dexron II ATF for T-5 trannys out of CJ's 1983-1986.

That is what I used in mine

 

[gijohn40]

Here is what was on cjoffroad....

I have done a decent bit of research on the "correct" fluid to use. A good friend is the Parts Manager at a local Jeep store and works with many mechanics who worked on these, I have looked over Factory Service Manuals from 1982, 1983, and 1984-1986, searched the Factory Recalls, and Tech Bulletins...

When they first came out, AMC recommended using ATF (1982 FSM). However, there was a recall for this in 1982 (Recall Number: 82V125000) indicating that the “ORIGINAL PRODUCTION TRANSMISSION LUBRICANT USED IN THE INVOLVED VEHICLES MAY NOT PROVIDE ADEQUATE LUBRICATION TO PROTECT THE TRANSMISSIONS FIRST GEAR.” FSM supplement for 1982 (Tech Bulletin) and the 1983 FSM both indicate to use 90wt in the T-5. By 1984, AMC started using a proprietary manual transmission lubricant. This was affectionately referred to as "fish oil" by the mechanics or AMC manual transmission fluid (Part Number 8983 000 000). This fluid was discontinued by AMC and currently, Chrysler is recommending the use of GL3 gear oil.

From my limited understanding, GL3 is very different from GL4 or GL5. I emailed Valvoline regarding this (as I haven't seen GL3 or GL4 in a very long time). They indicated that the issue is with the type of sulfate used in the lube. Apparently activated sulfate (used in some GL5 lubes) can eat brass synchros. Valvoline indicated: "The Valvoline High Performance Gear Oil 80-w90 can be used for both GL4 and GL5. The real concern is the type of sulfate used in the gear oil. You can not use an active sulfate for GL-4 applications. Valvoline uses an inactive sulfate that will not harm any yellow metal such as bronze. This allows our products to be used in manual transmissions that have bronze synchronizers."

All of this being said, there is an issue with shifting in colder climates. Apparently, the gear lube is almost too thick to allow smooth shifting on cold days, until the lube warms up a little. Many have reported good luck with synthetics, some have cut the gear lube with a little ATF, and some have reported good luck running 20w50 motor oil. I am not sure what the overall best solution is, but the only “Factory” recommended solution is to run 80-90…

 

[bobdog]

I would run Red line MTL (manual transmission lubricant). It will not hurt the syncros and is lighter than standard 90weight gear oil which the T5 will like. What I would really look into is the T18 swap I think to this day it is the best modification I have ever done to my CJ.