Arrrrgh!!! Mopar AX-5/AX15 GL-3 fluid!!!!

[Gary Allan]

Started hearing a few odd "worbles" from my wife's AX-15 when in OD ...decided to change out the fluid today. Now the FSM spec's GL-3 fluid. Try and find it. You can't. When I bought the thing, I did find one Mobil distributor that would sell me a 5 gallon bucket of Mobiltrans SHC 50 (a synth like the Mopar fluid) @ $110/5gallons. A relative bargain to the $15/quart dealer price.

Okay ..so I say "Heck, I'll just use one of the GL-4 jammers out there and take my chances" (apparently the GL-4 is nice to the soft metals too). Everywhere I went they wanted as much or MORE then the dealer for the synth GL-4.


So, $45 later...I have a fresh fill. The drain plug had a paste on it ..but no beard

 

[Pablo]

whats the dealer juice and howsit shift?

 

[Gary Allan]

Mopar label ...shifts smooth enough. The stuff in there (same stuff) had obviously thickened. Some have asserted that it's a Castrol product ..but I lean toward Mobil ..just due to the fact that they were the only one that I could find offering a synth GL-3 in the past

 

[99]

GL4 is what you want. GL5 is a huge no-no in these transmissions because it destroys the brass syncros. Redline MTL or MT90 is what you want and they're both AX friendly. Redline's been a "Jeep secret" for years now.

 

[Gary Allan]

I've been aware that other jeepers have used RL GL-4 ..but it's always been one of those "I used it and had no problems", type thing. It never was authoritative in just why it was suitable for use. If fact, until I point blank asked (after reading Molekules/Pablos post) "Do you mean to say that anything with an MT spec is okay for soft metals??" I had NEVER heard that this was a certainty. GL-5 hypoid had been in transmissions for all of my life ..they had yellow metals that didn't deteriate ..yet I needed "special fluid" ...so when some yahoo says "you can do this or that" without the "here's why" ...I can't just go along with it.

Funny, I have had a rough shifting 3 speed ..4 speed ..nor 5 speed that spec'd GL-4 90 weight hypoid. Since those long gone years we had all kinda of stuff (AFT, GL-4, GL-3, synth, etc.) all in a quest to get smooth shifting.

Where did we get lost

 

[99]

Use the GL4 lube with the utmost of confidence. It has proven itself over the years as being safe in these transmissions. Besides, there's not really all that many lube choices out there that aren't GL5. As for the GL5 issue, it most certainly destroys the brass syncros used in the AX transmissions. Maybe the metal in the trans is spec'd softer or whatever the case may be, but one thing is for certain, GL5 should not be used in these transmissions if you want a long, troublefree life out of them.

 

[Gary Allan]

Well, it will be good for future reference. Again, in this case (shoot from the hip - go out and buy it situation) the local offerings left the dealership as the most economical choice.

Thanks to all

 

[Zaedock]

Gary, believe it or not, I use Coastal 80W90 in my SM420 (I swapped it into my '92 YJ). It is rated GL3,GL4,GL5. My '420 shifted horrible with sulfer based gear oil that was only GL5 rated. I have no idea what Coastal uses instead of sulfer, but there is no grinding and shifts are smooth and precise (well, as precise as a dump truck tranny can get). It's also $6/gallon at AA.

Glad your AX15 is better.

 

[tdi-rick]

Gary, the OE fluid may be a Castrol product, as Castrol's excellent PAO/ester manual trans fluid Syntrans 75W-85 (11.9 cSt@100*C) is also GL3/4. This is blended in Europe and, I believe, here.
It is specced for many light and heavy vehicle transmissions, eg MB 235.4, MAN 341ZF TE-ML 02,01 (300,000km drain) and has a Volvo (truck) pt #, 97307

 

[Ryan00TJ]

I use an equal parts mix Redline MTL & MT90 in my AX5 and also my brother's AX15. It's a perfect mix and these trannys shift smooth as butter.

I feel sorry for the poor ******** that followed their owners manual that spec'd 75W-90 GL5 lube.

 

[MolaKule]

quote:

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GL4 is what you want. GL5 is a huge no-no in these transmissions because it destroys the brass syncros.

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Sorry, that's Hogwash.

Find a an MT Lube for your viscosity and use it whether GL4 or GL5 since most lubes are GL4/Gl5 and are backward compatible.

We have 4 different MT lubes; so one should be able to find one for your application.

 

[Gary Allan]

Mola ..I was just thinking ..man, if I had just needed this stuff a week earlier

Anyway, Mola, can you (or anyone) tell me the evolution from our former stout GL-5 brass laden transmissions and how they evolved to vulnerable GL-4/3 brass laden transmissions in the past 30 years.

I had no shifting issues with any manual transmission that had GL-5 hypoid in it. I always assumed that the AFT (brief) bout was for some CAFE thingy that showed up in the EPA economy cycle. I imagined that the ATF was abandoned in a helical arrangment due to lack of long term longevity issues.

 

[99]

"Sorry, that's Hogwash"

Nope. I'm 500% right on this one. Use a GL5 gear lube in a AX5 or AX15 trans and you WILL, I repeat, you WILL destroy the brass synchros. This is a well documented fact in the Jeep world. I've seen many a AX5 or AX 15 trans come in through the service dept and all cases that involve(d) poor shifting and grinding were caused by a GL5 lube being in the trans at the time or at one point in time. Jeep mistakenly put the wrong gear lube requirement in the service manuals and owners manuals and lots of people are running around with the wrong (GL5) lube in their transmissions. This has since been offically changed by Jeep and now those that know now know that these transmissions cannot use a GL5...only a GL3/4. I know this subject dead cold and how it pertains to the Jeep transmissions specifically, so to say I don't know what I'm talking about is just foolish.

 

[Ryan00TJ]

99 is right. DCX was in some crap from owners who followed their OM and used 75W90 GL5 oil and their tranny synchro's were shot. I've read numerous threads on JU about owners that have destroyed their AX trannys by running GL5 gear oil in them.

Redline talks about this problem right on their website.....

 

[Pablo]

It really depends on the GL-5 gear oil. An old fashioned high sulfur differential lube will not be very kind to certain brass/bronze alloys. New GL-5's with MT-1 rating including mola's, Amsoil SVG, etc will not harm proper brass alloys.

 

[Gary Allan]

This is where I think 99 is coming from. He's correct that the owners manual and the FSM disagree (I have the 99 FSM). The situation is that I do not believe that there was a GL-5 commonly available that wasn't hard on soft metals at that time. I had already installed M1 gear oil when I found this out and quickly swapped it to the Mopar stuff. At that point ...I think RL was the only one offering a synth that was acceptable.

So, I think that 99's experience is due to the use of non MT GL-5 fluid being used. The RL that was recommended was the same weight as 90 weight hypoid ..it was only lacking the nasties ..and it was a synth.

 

[Zaedock]

I purposely used GL5 in my old AX5 so I could swap it out for a real transmission: Muncie SM420.

Anyway, Coastal 80W90 (GL3,GL4,GL5 rated) from AA works for me. No crappy sulfer smell either.

Gary, swap out the AX15 for a T18...

 

[MarkC]

I was told by an Amsoil guy ( not Pablo) that Amsoil 75W90, even though GL5) didn't contain sulfur or anything else that would harm the brass i the AX-15, so I put that in mine about 5 years ago. No problems that I know of, other than that I probably need to change it out soon. It's as smooth as an eel's butt.
Not that I go around feeling eels...

 

[tdi-rick]

quote:

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Gary, swap out the AX15 for a T18...

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with a T98 granny first.....and no stinking synchros on frst gear either