AX15 - Gear Oil vs. Motor Oil (again)

[youngfred]

...

 

 

Rebuilt my AX15 and I am preparing to install.

 

Came in and did a Search for Gear Oil type

and learned a lot but - I am still not sure, just

what, to pour.

 

6.7 pints of :

Some say Motor Oil,

some say Gear Oil.

some don't like the smell,

some mention brass syncros,

some say - it-don't-matter.

 

Is there now, a general agreement ???

 

~

 

AX15 is going back into :

 

Stock

91 Eliminator

Two-Wheel Drive

4.0

Dana 35

 

Thanks

 

 

youngfred

 

 

 

[fiatslug87]

You'll get a bunch of answers, not sure of any consensus. I use Redline MT-90, seems to work well and others have also recommended it.

[youngfred]

5 minutes ago, fiatslug87 said:

You'll get a bunch of answers, not sure of any consensus. I use Redline MT-90, seems to work well and others have also recommended it.

...

 

 

Thanks.

 

This Stuff:

 

 

 

 

youngfred

[PIKE]

I have a 1996 Ford f350 with a 7.3 Powerstroke diesel and ZF 5 speed manual transmission. I go on several forums for this truck just like this forum for Comanches. Guys there do some crazy stuff from sled pulling, 5th wheel hauling, and giant flat beds.

The one oil that stands out far above is Redline MTL as the one that is most recommended.

 

Ford manual specifies synthetic ATF but the Ford OBS users vote for the Redline MTL

 

 MTL is the same as MT-90, MT-90 is higher viscosity.  

 

The Powerstroke guys like the MTL better for cold weather shiftability.

[Eagle]

The factory recommendation for the AX-15 was gear oil rated for GL-3. But GL-3 is no longer available, and the newer GL-4 and GL-5 formulations have more sulfur, which is what destroys the brass synchronizer rings in the AX-15. According to the parts guru at my dealership, the factory changed the recommended juice for the AX-15 to motor oil a number of years ago. The Redline MTL works well because it doesn't have the destructive high sulfur content.

 

I keep wondering if Pennzoil Synchromesh gear lube would work, but I haven't seen any reports of anyone trying it. Since my Jeeps are either before or after the AX-15 years, I can't test it even if I wanted to.

 

Out of curiosity -- does the AX-5 have the same problem with GL-4 and GL-5 gear lube as the AX-15? Logic would suggest that they're probebly built pretty much the same, but I naver hear of anyone having lube problems with the AX-5.

[Big Dan]

1 hour ago, Eagle said:

Out of curiosity -- does the AX-5 have the same problem with GL-4 and GL-5 gear lube as the AX-15? Logic would suggest that they're probebly built pretty much the same, but I naver hear of anyone having lube problems with the AX-5.

 

Yes, same issues for AX-4/AX-5

[fiatslug87]

The '90 owner's manual says "MOPAR Gear Lubricant or equivalent 75W90 (API GL-5)" I think the consensus is GL-5 is incorrect and should be GL-4.

The Red Line MT-90 is 75W90 GL-4 and their site says:

"Safe for brass synchros, as it lacks the reactive sulfurs found in most GL-5 oils that cause damage" &

"Satisfies the gear oil viscosity requirements of 75W90, 80W90, 90 and motor oil viscosities of SAE 40, 10W40 and 15W40" 

[FrankTheDog]

I put Mobil 1 10-30 High Mileage into my AX15 that had 175k on it and drove it another 100k with no trouble before I sold it. Never even checked the level in the trans that whole time. 6 years.

 

Just changed out the oil in the 2000 XJ with AX5 with Castrol Syntec High Mileage  10-30 and it shifts and drives normally for me.

[rokinn]

I went to a Redline distributor with the intention of buying MTL.  The guy asked if I would like him to look up the recommended gear oil for my MJ.  He said 75W90 NS (GL-5) was the proper oil for the AX 15.  I said many of the owners of MJ's recommended MTL.  He apparently is on a first name basis with the head scientist for Redline and gave him a call there and then.  The answer was the same, 75W90NS.  So that's what I purchased. 

 

I have to admit that 2nd gear is notchy until the oil warms up.  I can't say it was there before or not because changing the trans oil was one of the first things I did after purchasing it 2.5 years ago.  Next time I think I will go with MTL or possibly Amsoil just for comparison.  

[Jeep Driver]

Motor oil in the AX5 and it will be motor oil in the future AX15.

[DirtyComanche]

3 hours ago, rokinn said:

I went to a Redline distributor with the intention of buying MTL.  The guy asked if I would like him to look up the recommended gear oil for my MJ.  He said 75W90 NS (GL-5) was the proper oil for the AX 15.  I said many of the owners of MJ's recommended MTL.  He apparently is on a first name basis with the head scientist for Redline and gave him a call there and then.  The answer was the same, 75W90NS.  So that's what I purchased. 

 

I have to admit that 2nd gear is notchy until the oil warms up.  I can't say it was there before or not because changing the trans oil was one of the first things I did after purchasing it 2.5 years ago.  Next time I think I will go with MTL or possibly Amsoil just for comparison.  

 

What is 75W90NS specifically?

 

 

Edit, it's GL-5 without friction modifier.  Friction modifier isn't an issue either way, at least not that I'm aware of, since it really only affects clutch pack/cone friction surfaces, and an AX-15 doesn't have those...

[PIKE]

41 minutes ago, DirtyComanche said:

What is 75W90NS specifically?

 

https://www.redlineoil.com/75w90-ns-gl-5-gear-oil

[DesertRat1991]

'91 Owners Manual also says Mopar fluid/ 75W90 (API GL-5).  

 

But, I ultimately went with Redline MT-90 GL-4 after sifting through feedback on various forums. Very happy with the results.  It's difficult stuff to find locally, but Amazon prime will get you a large bottle in 2 days.

[youngfred]

15 hours ago, DesertRat1991 said:

'91 Owners Manual also says Mopar fluid/ 75W90 (API GL-5).  

 

But, I ultimately went with Redline MT-90 GL-4 after sifting through feedback on various forums. Very happy with the results.  It's difficult stuff to find locally, but Amazon prime will get you a large bottle in 2 days.

...

 

 

Thanks DR,

and thanks for all...

 

A lot of good stuff, here.

 

I will go with the Redline MT-90.

 

~

 

Gotta go, pick up ole John Henry,

and smash lots more cans,

till I can get enough.

 

 

youngfred

 

 

[A-man930]

I've had Royal Purple 5w30 in mine for over 7 years now.  Local Jeep shop did an overhaul on it back in the day and that's what they recommended.  Only changed it once and that's because the truck went for a swim 

[Pete M]

On 11/17/2017 at 11:00 PM, DesertRat1991 said:

'91 Owners Manual also says Mopar fluid/ 75W90 (API GL-5).  

 

 

eventually superseded by chrysler who changed it to 10w-30 full syn

[87Warrior]

I dumped GL-5 gear oil in an AX15 in a YJ I had in high school. As most folks do, I was simply trying to preserve it for years to come and relied solely on the Chilton manual for advice. Within 1 year of the gear oil change, I had to have the transmission rebuilt since most of the synchros were toast. I sold that Jeep a few years after the rebuild (filled with synthetic 10w-30) and it was working fine.

 

I also run synthetic 10w-30 in the AX5 in my 86 MJ. 10w-30 is cheaper than the Red line fluid, is readily available everywhere and is what Chrysler recommends for the transmission... I see no reason to play 'gear oil roulette' with my transmission. I do run the Penzoil Syncromesh in the NV3550 in my TJ and have noticed the bottle indicates it is safe for yellow (or soft) metals.

[ComancheKid45]

Have had syncromesh in my AX15 for 7 years now, given the fact the truck only gets maybe 500 miles a year on it, I've had no issues.

[Minuit]

10W-30 synthetic in my AX-15. After getting rid of what I assume must have been GL-5, it shifts a little better.

[Jtrux]

Pennzoil Synchromesh was recommended to me by Rockland Standard Gear where I bought my Jeep Termimator transmission from. Seems to be holding up after 55k.

Sent from my LGLS992 using Tapatalk

[kook911]

So it seems there is half that say MT90 and the other half say 10w30. So I’m going to guess that you can run either and be fine?  

[DirtyComanche]

4 hours ago, kook911 said:

So it seems there is half that say MT90 and the other half say 10w30. So I’m going to guess that you can run either and be fine?  

 

Probably.

 

 

 

I'll be putting synthetic motor oil in mine next time.  Maybe not 10w30.

[mjeff87]

I ran MT90 and 10-30 in mine (and also some Mobil 1 75/90 at one point).....I honestly couldn't tell any difference.  FWIW, 10-30 is cheap compared to the others, and is/was my preference.

 

Jeff

[kook911]

So any brand of 10w-30. I'm assuming full synthetic.

[Pete M]

I'm sure chrysler says Mopar brand oil, but yes, any full syn should do.