Transmission and T-Case Fluid

[500 MJ]

Do we have a thread anywhere that discusses the factory recommended fluids for our transmissions and t-cases?  I’m sure that there are many other opinions on other fluids for them as well... 
 

I looked for a few minutes, did a few searches and could not come up with anything directly addressing this based on the search criteria that I used.

[jdog]

Which trans and tcase

Ax-15 is gl4 fluid,  tcase is just atf

I believe that aw4 takes  atf 3/4

 

[scaleless]

Speaking of, this stuff is the bee's knees!

https://www.amazon.com/Red-Line-50305-MT-90-75W90/dp/B002INX20C

[ghetdjc320]

I’ve been using straight 30 weight motor oil in the tcase for a long time now. Excellent results. 10w-30 also works great in an ax15 and I believe a Mopar TSB even recommended it iirc.

[cruiser54]

Make sure you don't use the Chrysler fluid in your AW4 auto trans!!

Regular old Dex/Merc ATF.  And, you only need to do a drain and fill using the pan plug. Takes about 3.8 quarts.

 

[jdog]

2 hours ago, cruiser54 said:

Make sure you don't use the Chrysler fluid in your AW4 auto trans!!

Regular old Dex/Merc ATF.  And, you only need to do a drain and fill using the pan plug. Takes about 3.8 quarts.

 

I stand corrected, it had been a while since I had to deal with the aw4. Couldn't remember if it was dex merc or atf3

[75sv1]

19 minutes ago, jdog said:

I stand corrected, it had been a while since I had to deal with the aw4. Couldn't remember if it was dex merc or atf3

I'd also probably avoid a Full Synthetic in the AW4. The ATF+4 I think is a Full Synthetic. There are Dex2/Mercon that are Full Synthetic. I think some of the GM guys use it in some of the GM trans. Not sure how well they would work in the AW4. I would use a Full Syn in the TC case. 

[AZJeff]

28 minutes ago, 75sv1 said:

I'd also probably avoid a Full Synthetic in the AW4. The ATF+4 I think is a Full Synthetic. There are Dex2/Mercon that are Full Synthetic. I think some of the GM guys use it in some of the GM trans. Not sure how well they would work in the AW4. I would use a Full Syn in the TC case. 

I used fully synthetic Dex/Merc in the AW-4 on my 2000XJ and changed it every 25K miles.  The vehicle used this stuff for over 100k miles, with no issues.  

 

My current MJ is using conventional Dex/Merc, and I just change it more often, due to the heat issues here in Phoenix.

[Tex06]

17 hours ago, scaleless said:

Speaking of, this stuff is the bee's knees!

https://www.amazon.com/Red-Line-50305-MT-90-75W90/dp/B002INX20C

X2 for redline, it's great stuff I use in my high end vehicles(the MJ doesn't fall in that category, lol).  I use Pennzoil GL-5 in my AX-15 now. I ***DO NOT*** recommend running a motor oil in the AX-15. I did for about 3000 miles and recorded much higher transmission temps while doing so as compared to the GL-3 (or whatever was in there previously) and the Pennzoil GL-5 immediately after.  Higher temps mean more friction, more friction means more wear happening.

 

My $0.02

[scaleless]

42 minutes ago, Tex06 said:

Pennzoil GL-5

GL-5 absolutely destroys yellow metals like the brass synchros in the AX15 and is not intended for use in synchromesh transmissions - I would drain that in favor of GL4 as soon as possible.

[ghetdjc320]

Lol, these topics are always a can of worms. So many opinions and different experiences. Many will say x oil gave them 100’s of thousands of trouble free miles while others will say that x oil destroyed their tranny & tcase etc. Many won’t trust even the manufacturers recommendations these days and occasionally that’s for a good reason.

 

At the end of the day it will just be up to you because the suggestions will never end. I hate to say it but this is one of those topics that requires you do your own research instead of going strictly off of what your pears say. Otherwise this is about as subjective as health advice, in other words, everyone has an opinion and, of course, some great reason for believing their opinion. 

 

[Tex06]

17 hours ago, scaleless said:

GL-5 absolutely destroys yellow metals like the brass synchros in the AX15 and is not intended for use in synchromesh transmissions - I would drain that in favor of GL4 as soon as possible.

Not true. Depending on the manufacturer depends on if and how much sulphur/phosphorus is used (which is what attacks "yellow metals" such as brass, copper, and bronze). There are brands of GL-5 that meet the wear spec without the use of sulphur, Pennzoil is one of them. I believe the spec you want is GL-5/MT-1, with MT-1 distinguishing that it is yellow metal safe. I've run this for nearly 7 years with no ill effects as have many many others.

For information on this, look at the independent testing done and recorded on bobistheoilguy.com where they break down gear oils that are yellow metal safe. Even the absolute worst GL-5 would take years to eat the synchros to a point that it would affect shiftability. I look at it akin to "Water corrodes aluminum and iron, yet look at how many uncoated aluminum transmission cases and cast iron rear ends there are in the world".

 

Full disclosure: I'm a Materials Engineer and deal with corrosion in my day to day. 

 

Edit: Pennzoil SynchroMesh is what I'm running. They may not make it anymore with a GL certification from what I'm seeing online, it's now just listed as an MTF (Manual Transmission Fluid).

[Tex06]

15 hours ago, ghetdjc320 said:

Lol, these topics are always a can of worms. So many opinions and different experiences. Many will say x oil gave them 100’s of thousands of trouble free miles while others will say that x oil destroyed their tranny & tcase etc. Many won’t trust even the manufacturers recommendations these days and occasionally that’s for a good reason.

 

At the end of the day it will just be up to you because the suggestions will never end. I hate to say it but this is one of those topics that requires you do your own research instead of going strictly off of what your pears say. Otherwise this is about as subjective as health advice, in other words, everyone has an opinion and, of course, some great reason for believing their opinion. 

 

Yeah, I agree. That's why I point people in the direction of research instead of just saying "Trust me, I'm an engineer!" 

[75sv1]

On 5/6/2021 at 11:53 AM, AZJeff said:

I used fully synthetic Dex/Merc in the AW-4 on my 2000XJ and changed it every 25K miles.  The vehicle used this stuff for over 100k miles, with no issues.  

 

My current MJ is using conventional Dex/Merc, and I just change it more often, due to the heat issues here in Phoenix.

Good to know. Still, I used ATF+4 in an AW$ with no issues for a few years. Others did have issues. I did have issues latter with that trans. It was the rear speed sensor. So, not an issue with the fluid. Also, I run an Aux cooler. My next or project XJ is getting two coolers. One before the Radiator and one after.