Manual Tranny/Diffs

[Ritter4.0]

Is it ok to top off the diffs and manual tranny with 80w90? Or will it cause damage? I probably wont be draining them anytime soon unless a greyish color is bad. I searched it and didnt find much. I have a 1990 4.0 manual tranny.

 

[RCP Phx]

Why would you think it is anything else but?

 

[5-90]

Use GL-3 in the gearbox, and GL-5 in the axles. Why? Because GL-5 contains high levels of sulphur (as an Extreme Pressure lubricant) - this is good for the axles, but not so good for the transmission. Sulphur is antagonistic to "yellow metal" - like the bronze synchroniser rings in the gearbox.

 

[Ritter4.0]

Thanks, also sometimes it is hard to get into 1st gear, it never jumps out, just hard to get in, what would cause this? Anything really serious?

 

[89xj]

Use GL-3 in the gearbox, and GL-5 in the axles. Why? Because GL-5 contains high levels of sulphur (as an Extreme Pressure lubricant) - this is good for the axles, but not so good for the transmission. Sulphur is antagonistic to "yellow metal" - like the bronze synchroniser rings in the gearbox.

Thanks, also sometimes it is hard to get into 1st gear, it never jumps out, just hard to get in, what would cause this? Anything really serious?

gl-5 in the trans can cause the shifting into first problem or too thick of gear oil.

look for redline mtl or mt-90 for the trans. if your in a really cold climate, i would use mtl as it is a bit lighter than mt-90

 

[lawsoncl]

x2 on the MTL or MTL-90. Hard to get it into 1st when cold is often just using the wrong oil.

 

[joe_peters]

According to what others have posted here, Jeep now recommends 10w30 motor oil in the AX15 transmission.

I am going to try Mobile-1 10w30 in mine.

 

[lawsoncl]

Viscosity-wise, its reasonably close. Please post back whether you see any improvements.

 

[joe_peters]

Ok, changed my AX15 to Mobil-1 10w30 today.

Will make a 210 mile trip Friday and will post shift improvement/noise improvement observations Friday evening.

 

[outlander]

subscribed.....curious to see how well the 10w30 works in the ax15.

 

[chedisme]

subscribed.....curious to see how well the 10w30 works in the ax15.

same here

 

[BudgetXJ]

same here

x3

 

[joe_peters]

Update: took her for a quick three mile run. I would say the improvement in shifting was positive, but the long trip will really let things warm up.

Not to sure about noise. My center console is out including the tunnel boot so its hard to tell.

More tomorrow.

 

[Ritter4.0]

My tranny was not as low as I had thought, but my t-case was very low, almost dry, If anybody cares I had a hard time using the "transmission funnel" so I made my own. I used a cap from a dish soap bottle (Dawn) and small rubber hose. it fit perfectly on the oil bottle and I just squeezed it in. Im also curious about the long term effects of 10w30 in the AX-15. My first gear problem is probably more due to me using it as a parking brake, all the time (my real one doesnt work).

Use GL-3 in the gearbox, and GL-5 in the axles. Why? Because GL-5 contains high levels of sulphur (as an Extreme Pressure lubricant) - this is good for the axles, but not so good for the transmission. Sulphur is antagonistic to "yellow metal" - like the bronze synchroniser rings in the gearbox.

I looked at my manual and it says to use GL-5 in the Tranny, I know you have way more experience and knowlege about it so why would the manual say to use the GL-5? Is that why they now reccomend 10w30?

 

[joe_peters]

Not quite sure of the reason why, I got the impression that the sulfur content of the gear lube may be having adverse reations with the yellow metal synchros in the AX15. Mopar had a reason, how sound who knows. There is a long discussion at http://www.naxja.org/forum/showthread.php?t=935886 note that this is a long dead thread and don't embarrass yourself by posting to it--like I did!

My hopes for the 10w30 is to eliminate the hard shifting of the gear box, most particularly 1st gear.

 

[Ritter4.0]

Thanks, do you use your 1st gear as a parking brake too? Im just curious.

 

[joe_peters]

No. Kind of a parking brake fanatic ever since my brother let his 59 Plymouth roll backwards into my 53 Willy's rear quarter panel. That was around 1967, but who holds a grudge.

I do put it in 1st or reverse, but the brake is doing the work.

 

[Ritter4.0]

Well mine needs some work, cause its currenttly a black clicking lever. I have already tightend the cables, so it has to be in the brake drums. I always park my XJ on a very slight hill at my house, and to keep it from rolling into my moms van I put it in 1st and slowly let off the brake petal so it doesnt slam the gears. Not sure but this could be causing my problem. I will find out after I change my tranny fluid for something better, not sure what the PO put in it, but it is kinda brown and dirty looking.
Thanks for your input so far.

 

[lawsoncl]

I doubt using 1st to hold the vehicle (it won't, btw) should cause any harm to the tranny or the synchros.

 

[joe_peters]

Ok, here is the official unofficial report:

After 214.9 miles since changing from GL to Mobile-1 10w30 my AX15 shifts better, and I mean noticeably better.

The added bonus is a reduction in noise. As stated earlier, my center console and tunnel boot are not installed at this time. Well, after about 50 miles of the trip I started noticing different noises inside my XJ--small air leaks, empty soda can rolling around, and some junk rattling in the glove box! These are sounds I never heard, or was unable to differentiate them over the trans noise. Totally subjective and "in the ear of the beholder", but I swear it is quieter.

So there you are, the official unofficial and wholly subjective road test.

I would do it again in. Would you get the same/equal results with a 10w30 non-synthetic oil, I don't know.

In closing let me say that this is not a miracle fix--I still have dandruff and athletes foot, so it certainly doesn't fix everything!!