[jimmy]

i have a simple question, what type of fluid do i use in my 5 spd trany, some say gear oil and some say atf? 86 cj7
thanks for any input.

[Rollbar]

75w90 - 85w90 gear lube.

[MikeJoel]

yeah,85w90 gear lube are great

[JeepinIan]

ATF is the fluid needed. There are needle bearings in ths T-5 that will not get lubed if you use gear oils such as mentioned.

[jimmy]

see what i mean, ATF or gear oil??

[Big Red One]

Found this on a Forum...
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The problem with T-5 is very complex. From what I have read, the T-5 is rated to 265 ft-lb torque, the AX-15 is rated to 285 ft-lb, and the NV3550 is rated (conservatively) at 300 ft-lb. So, if it is nearly as strong as the AX-15, why does it have such a bad reputation?

I hit the website for http://www.5speeds.com/ talk about a shop that knows their T-5s...the guy was very very knowledgeable! He indicated the largest problems (that gave T-5s a bad rap) dealt with a recalled third gear (went from 29 spline to 27 spline). That upgrade is supposed to help beef the thing up a good deal. Other problems deal with incorrect or improper fluid levels. These non-world class transmissions operate without needle bearings (instead having deep oil grooves). As such, they should only run gear oil.

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…

I hope this was not too confusing, I have researched it a lot and written a similar dissertation in a lot of other forums. This is a little more concise...

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Also read that RED LINE MTL 75w/80w was a choice of many and they had 100,000 miles or more with no problems, the Red Line meets the requirements of GL-3 / GL-4 motor oil viscosities SAE 5W/10W/30 AND viscosities of ATF'S

Sounds like a good quality synthetic gear oil is the way to go...

[jimmy]

That was fast, thanks for the great info!! now i know what to use. i knew there was a debate on what to and not to use.

thank you very much

[Krocker]

I'll go for 85w90, I've been using that for a long time.