AX-15 questions

[gogmorgo]

Just goes to show how rumours and misinformation can spread. However it’s something I’ve seen about GL5 oils not just in a Jeep context. It was common knowledge on the Lada forums 20+ years ago. This is the first I heard about friction modifiers causing issues however. The concern is usually corrosion on the synchros from the extra sulphur additives. 
 

Deteriorating synchros definitely lead to degrading shift properties. 
I’m pretty sure the 10w30 was better than whatever it was a drained out of the ZJ when I got it, but I don’t remember anything about what came out of it. 
When I did the clutch in my mj last winter it definitely did worse with the engine oil in the AX5 than it did with whatever was in it before. It was bad enough I drained it for the royal purple a week later. 

[89 MJ]

46 minutes ago, Minuit said:

Don't forget that 75W-90 gear oil is equivalent to a 10ishW-40ish motor oil in viscosity. That's not really a fair comparison, but just putting it out there.

 

To add some more hearsay and conjecture onto the pile, my AX-15 shifted considerably better with 10W-30 conventional than with the gear oil of unknown weight I drained out of it. I think the "use 10W-30 motor oil in the AX-15" thing is much more about syncro corrosion than shift effort or anything else - and 10W-30 just happens to be what is normally used in the 4.0L engine, so you could use your engine oil in the transmission.

Ok. That’s interesting. I didn’t know that. 

 

43 minutes ago, eaglescout526 said:

 

I looked a little bit further and found this. I remember finding this but kinda forgot about it because all it says is the motor oil helps with shifting properties. Nothing about the synchro's 

Perfect, this is pretty much what I was looking for. 

[89 MJ]

17 minutes ago, gogmorgo said:

Just goes to show how rumours and misinformation can spread. However it’s something I’ve seen about GL5 oils not just in a Jeep context. It was common knowledge on the Lada forums 20+ years ago. This is the first I heard about friction modifiers causing issues however. The concern is usually corrosion on the synchros from the extra sulphur additives. 
 

Deteriorating synchros definitely lead to degrading shift properties. 
I’m pretty sure the 10w30 was better than whatever it was a drained out of the ZJ when I got it, but I don’t remember anything about what came out of it. 
When I did the clutch in my mj last winter it definitely did worse with the engine oil in the AX5 than it did with whatever was in it before. It was bad enough I drained it for the royal purple a week later. 

Hmm. Ok thank you. Definitely a lot to consider. 

[Pete M]

whether you use the redline or the syn 10w30 you'll be good to go.  

[JMO413]

I am definitely a fan of Redline.

 

 

[eaglescout526]

I have an AX5(duh) but I have been running Mopar 75w-90 in it for a few months now. No problems. 

[MercManche]

22 hours ago, JMO413 said:

I am definitely a fan of Redline.

 

 

Bump^ Run Redline MT Fluid plus some lucas in all my AX-15s and even in my NV4500.

My cherokee AX15 has just over 260k with no issues. I would never run gear oil in a manual transmission, just doesnt work right for protecting the gears & synchros. 

Proof of this? Go to your local parts store and dig up the old lucas oil hand crank, notice the difference in how the oil lubricates the gears differently. 

Get a AX15 post 92 so you are guarenteed the 3/4" input shaft and external slave cylinder. If the damn NSG370s wernt so rare I bet a 6 speed comanche would be a hoot to drive!

[Pete M]

the ol' hand crank counter display is... let's say "less than ideal" for determining what any particular oil does when at operating temp and the gears are spinning at a million rpms.   

 

as I understand it, 10w30 (or is it the 40?) is actually quite close to 75w90.  engine and gear oils just have different nomenclature scales or some such thing.  if it's good enough for Mopar to suggest it, it's good enough for me.    but it's certainly not any better than the redline so it's all good no matter what is chosen.