Well time has come to change the manual tranny fluid in my 97 wrangler with 5 spd manual ax5 tranny. I've been running into an issue tho. according to the manual it takes 75w90 GL5 tranny fluid. but apparently the factory service manual states not to use GL5 because something about it can deteriorate synchros (extra additives hell i dunno?) but i've never seen the FSM so I dunno how true that is. and theres tons of things on jeep forums of people arguing it and it seems split down the middle like 50/50 so i'm confuzzled as all heck. I don't see how there could be that big of a difference between GL4 or 5 and i've also heard that GL5 meets requirements for GL4 as well but once again I dunno how true that is. Also none of the big names make a GL4 fluid. I've checked mobil 1, amsoil, royal purple, so far all i've found is a company called Redline and i've never used any of there stuff. ops on them. so the big question is what's the diff between GL5 and 4???

 

Ben, synchros are just little gears that get the main gears up to the right speed so you can shift smoother. I can't see how GL5 would deteriorate them, whatever that means. I use the Amsoil online application guide, and they call for GL5 gear oil for your manual transmission.

 

It didn't make sense to me either I mean what could possibly be wrong with gl5 lube??? I dunno I called the dealer to see if he would check the fsm for me. he woudln't he checked some other book and told me to use 10w30 motor oil. needless to say i won't be doing that lol.

 

call napa or carquest. if the dealer cant see straight to find the proper info, maybe they be a bit funky there...


could laways call royal purple and talk to them.

 

first thing you need is a competent service guy, i looked in the chrysler service manual and it does say to use GL3 75w90 gear oil, if you look
on a chrysler lube chart in our parts dept it says to use special ax5/ax15 gear lube wich is part number 4897622AA.it also says 4897622aa is 75w90 gear oil as far as the GL numbers each higher number to get the classification has to be able to service the lower numbers, so GL5 will replace GL3 without question. i am the parts manager at a dodge dealer i am open to any questions like this. i will try to find the real info not just a generic answer.there is also a tsb on this gear oil 4897622aa to use 10w30 motor oil for improved shifting. import cars have been doing this for years so after a long answer 10w30 is the thing to use.

 

10w30 motor oil?? I just can't see how that works and I don't have any problems shifting it just needs a change. see i thought that too Gl numbers are backwards compatible gl5 has to work with 3 and 4 and so far the only gl4 lube i found is redline.

I just don't see how motor oil could possible work I mean it would just not be close to thick enough to work i'd think i'm confused.

 

most oil manufacturers wont continue to sell the lower gl number once there is a new standard. the only thing i can tell you on the gear oil is
the 4897622AA original number has been discontinued and replaced by 10w30. we are only a dodge dealer and dont see many jeeps
maybee someone on here from a jeep dealer can shed some light on this. years ago i worked at a trans shop doing r&r on transmissions
and a lot of imports use motor oil not gear oil. when most of the american cars went to atf in standard transmissions it worked great. hope this info
helps you not just ad more confusion.