AX-15 hard to shift when hot.

[docboy209]

I've searched the net for the correct fluid for the AX-15 and have seen many posts about a Red Line fluid. Many people complain about cold weather shifting into 2nd. My complaint is when the tranny is at "operating temp." It gets hard to shift into any gear directly :banghead: It's especially harder if I make a stop along the route (gas, groceries, etc). It gets easier if I let it go into N and then shift into the next gear, but that adds a second to every shift and the rpms just drop off. Would a fluid change help this? And if so, what fluid would you all recommend? I have easy access to Honda MTF!

Unrelated, but has anyone with a 231 t-case had the snap ring just behind the rear output bearing break? I did. A piece of it took out the seal and it flung ATF right onto the cat. Nasty smoke poured out everywhere!

 

[cwstnsko]

AX-15 likes GL-4 gear oil, not GL-5.... GL-5 is hard on the synchros. You also don't want any Limited Sip additive in the oil, which rules out most of the common auto parts store gear oil. I haven't looked lately, but NAPA used to sell GL-4 gear oil and I believe GM Sychromesh is GL-4.

 

[jcshaney]

I found when i called the local jeep dealer they used two different fluids in a ax15 change i think happened in 97 one was gl4 like previosly mentioned if memory servs the newer ones use atf but sounds to me that the clutch is not relesing all the way just my 2 cents

 

[joe_peters]

The gen-u-ine specified gear oil is GL-3.

GL-5 will EAT yellow-metal synchros, and that is what is in the AX-15. Don't use GL-5.

Only use YELLOW-METAL SAFE lubricants in the AX-15. GL-4 is not what you want to use.

You can use Penzzoil Synchromesh, it is yellow-metal safe and is marked as such on the bottle, about $8 per quart.

You can stop by the dealership and purchase the special synthetic fluid they now have for the AX-15, about $22 per quart.

You can use ANY quality synthetic 10w30 motor oil, about $4 per quart. I run Mobil-1.

you can use Red Line MTL-90, about $12.49 per quart on-line.

Amsoil makes something, not sure of the name or cost.

Royal Purple makes something, not sure of the name or cost.

GL-3 is very hard to find, try NAPA or some truck stops, might have to buy a 5 gal bucket.

AVOID GL-3/GL-4/GL-5 combo products unless the container is specifically marked "YELLOW METALS SAFE".

You FAILED to provide your BASIC info--year/engine/mileage/mods/recent work done/etc.

How many miles on the clutch? Has the flywheel ever been surfaced?

When was the last time you flushed the fluid from the MC/slave? Brake/clutch fluid is hygroscopic--it sucks moisture from the atmosphere, brake and clutch hydraulic systems should be flushed every two years or so.

 

[crimsondragon]

I run Shell dino 10W-30 in the AX-15. Shifts fine but it does have the hard to shift when cold issue. Usually goes away once it gets going.

 

[cwstnsko]

Thanks for correcting my misinformation Joe, I knew the GL-5 and limited slip additives were bad news, but my memory failed me on the GL-4 vs GL-3 part.......

 

[lawsoncl]

I initially used the NAPA GL3 oil after I rebuilt my AX15. It shifted so bad I thought I screwed up the rebuild. Swapped out to Redline MTL and it shifted beautifully. I've heard of lots of people being happy with Mobil1 motor oil.

 

[austinaubinoe]

oh crap, I put some mobile-1 75-90 in my dads AX-5 (4 banger TJ) 6 months ago! Pretty sure it said GL-5 on the bottle.

I just changed the oil on my moms Toyota sequoia, so I have some mobile 1 5W-30, would that work? OR I have some Dino coastal gear oil in a 5 gallon drum that I usually put in my diffs.

Thanks.

 

[joe_peters]

oh crap, I put some mobile-1 75-90 in my dads AX-5 (4 banger TJ) 6 months ago! Pretty sure it said GL-5 on the bottle.

I just changed the oil on my moms Toyota sequoia, so I have some mobile 1 5W-30, would that work? OR I have some Dino coastal gear oil in a 5 gallon drum that I usually put in my diffs.

Thanks.

I'm not sure if the AX-5 has yellow-metal synchros, so finding that out would be the first step.

 

[lawsoncl]

I'm not sure if the AX-5 has yellow-metal synchros, so finding that out would be the first step.

Yes it does. Skip the Coastal gear oil as it's likely GL5 as well. I'd go with the Mobil1 5W-30

 

[docboy209]

Sorry that I forgot "the basics" Joe Peters. It's a stock '98 4.0L (the only engine that had the AX-15aper with 130K and I just replaced the t-case. The shifting problem started well before I replaced it though.

The clutch is fully releasing.

 

[RichP]

I run redline now, tranny has over 350,000 mi on it. I run mobil-1 ATF in the NP231, same age/mileage. When I change the tranny fluid again next year it will get Mobil-1 10W30 or 10W40. It's nice all 4 jeeps taking the same oil filter, same oil, now the same tranny fluid cept for the 97 Grand.

 

[NH_Jeep_XJ]

From My OEM Owners Manual - 98 XJ built September 97

Manual Transmission

Recommended Fluid:
Fluid Type: Use only Mopar Gear Lubricant (P/N 4549624) or equivalent SAE 75W-90 API-GL5 grade.

This would make sense if the Mopar Gear Lubricant doesn't have the limited slip clutch additive and why it is added separately for the Trac Lok differential as I have.

Also, as to why the off the shelf GL5 75W-90 might not meet specs because they commonly do have this additive which apparently is what isn't good for the yellow metals.

 

[joe_peters]

From My OEM Owners Manual - 98 XJ built September 97

Manual Transmission

Recommended Fluid:
Fluid Type: Use only Mopar Gear Lubricant (P/N 4549624) or equivalent SAE 75W-90 API-GL5 grade.

This would make sense if the Mopar Gear Lubricant doesn't have the limited slip clutch additive and why it is added separately for the Trac Lok differential as I have.

Also, as to why the off the shelf GL5 75W-90 might not meet specs because they commonly do have this additive which apparently is what isn't good for the yellow metals.

That GL-5 recommendation was a MAJOR screw up by Chryco--yes, it happens folks--and it is still being repeated at chain parts stores all over the country.

GL-5 WILL EAT THE YELLOW-METAL SYNCHROS IN TRANSMISSIONS. GL-5 IS NOT COMPATIBLE WITH YELLOW-METALS. IF YOU WANT TO DESTROY YOUR TRANSMISSION, AND IT HAS YELLOW-METAL SYNCHROS, THEN GO AHEAD AND USE GL-5--THE RESULT IS GUARANTEED.

 

[lawsoncl]

From My OEM Owners Manual - 98 XJ built September 97

Manual Transmission

Recommended Fluid:
Fluid Type: Use only Mopar Gear Lubricant (P/N 4549624) or equivalent SAE 75W-90 API-GL5 grade.

The owners manual is wrong. Don't use the Mopar oil either.

It's the sulfur based EP additives in GL5 that are the problem. When the gear oil gets old or overheated, the additive breaks down and the released sulfur attacks the brass synchros. Some GL5 rated oils use other non-sulfur based additives and are okay to use, but it's hard to tell which ones and they could always change the ingredients.

http://www.synthetic-oil-tech.com/Gear%20Lube%20White%20Paper.pdf This article is a really good read and demonstrates the problem and does a good comparison of gear oils. The article is meant to rate gear oils for differential use, but the section with the ASTM D130 test is very enlightening as it shows . Take the final conclusions that AMSOIL is the best thing since sliced bread with a small grain of salt though, as AMSOIL funded the study.

In any case, I would not use anything meant to be used in a differential as the EP additives are also what screw up the shifting as they have a low coefficient of friction under pressure. You want some friction under pressure so the synchros can do their job. You also want a low viscosity when cold, which is where synthetic oils excel.

Some more articles worth reading:
thread http://www.naxja.org/forum/showthread.php?t=935886
Redline White Paper http://www.redlineoil.com/content/files/tech/Gear Oil Tech Info.pdf
Redline White Paper http://www.redlineoil.com/content/files/tech/MTL and MT-90 Tech Info.pdf

 

[docboy209]

Well, I'm experimenting with Honda Genuine Manual Transmission Fluid as I now work at a Honda dealer and it's basically free to me. I checked that Red Line MT90, and it seems to be the same as the Honda stuff. I'll let you all know how it goes.

If it can handle the abuse of a turbocharged S2000, it should handle a stock XJ daily driver.

BTW, the fluid had about 75,000 miles on it, and came out kinda dark. No metal particles, and the magnet had the normal amount of gunk on it.

 

[docboy209]

Went driving around a lot last night trying to :gee: (beat the crap out of it). No change. Guess I'll have to crack it open and check/replace the synchros. Oh well.

Hey Lawsoncl! That Amsoil test article was very informative. Thanks, definitely a good read!

 

[ktwalker01]

If you were to take your xj with an ax-15 to the stealership today for a tune up and if they were to change your tranny oil they would put synthetic 10w-30 in it. Ive been running mine with 10w30 for 60k miles now no problems.

 

[gradon]

I think your issue is the seals in the master cylinder. When it gets warmed up(the header is right there), the brake fluid gets thinner and doesn't apply as much pressure.

 

[Distended]

FWIW: Changed 1996 ax-15 manual transmission fluid yesterday. After reading many a post on many a forum, I decided to go with with RP 10w-30. But just before draining old fluid, I called my local Jeep service rep. and he said they just had a '98 Cherokee in the day before and the service dept. used 10W-30.