diff. fluid mistake??

96 xJ

changed both diff.'s yesterday - used off the shelf 80W90 gear oil, i think it's gl-3 grade, but didnt think it was a big deal until i read some of the posts...

should i worry?

also - putting 75W90 Gl-3 in my manual transmission
AND - dexon III auto trans. fluid in my transfer case.

sound good?

I don't think that it, GL rating, makes much difference in the diffs, the only variables are if you have a limited slip that requires the friction modifier in which case you limited slip if you have one won't work right till you add it.
In the AX15 and AX5 manuals are a different story, no idea about the NV trannies.
What brand of GL 3 fluid did you get for the tranny ?

IFIRC, the AX-15/AX-5 issue about GL-3 vs. GL-4/GL-5 Fluid is that GL-4/GL-5 have additives that can be corrosive to the brass synchros. There were mistakes in the driver's manual stipulating the use of GL-5, but actually the manufacturer of the tranny has and still calls for GL-3 for use in the tranny.

Something I read on the RedLine Synthetic Fluid site is that if GL-4/GL-5 fluid reaches a certain temperature, the fluid becomes corrosive to the synchro. Might explain why there is varying results, some have had their synchros eaten up by GL-5, others have used it for years with no problems. I suspect, those that got by fine, never got their tranny fluid hot, while those that had their eaten up did get their fluid hot, either off roading or towing, etc.

Concurr with RichP on the differential, differentials are under a lot of pressure, the higher the GL the better they stand up to the pressure. Synthetic Diff Fluid also has a lot of advantages for diffs, they stand up to the pressure like GL-5, but flow better cold like a GL-3 and thus you get the best of both worlds.

The Limited Slip, that has clutches in it, which is most of them, needs a friction modifier (make it more slippery). If you have an LSD, then you need to buy the Friction Modifier as an additive and add it to the diff or buy the exact recommended fluid.

Use the wrong fluid for a LSD and the clutches won't grap right, you'll get noise and shock in the drivetrain, and tires can even break loose during turns from the clutches disengaging/engaging incorrectly.

cool - i dont think i have the track-lock lsd system - mine is a 96 cherokee sport...how would i know if i have lsd?

and to clarify - it's dexon iii in the transfer case, and 75w90 gl-3 in the manual tranny?

Put the wheels in the air, frame or axle on jackstands, parking brake off, trans engaged. Turn one wheel, if the other turns in the opposite direction, its an open differential (non-LSD). If you can't turn the wheel, its trying to back drive the driveshaft, then its an LSD.

The clutches are holding the two rear wheels in synch, it takes a lot of force to break the clutches free and let the rear wheels spin independently. You can have a friend grab the other wheel and try to spin it in the opposite direction, an LSD makes enough force, that if a person can break it free at all, they'll be grunting and groaning. Non-LSD, Open Diff, takes almost no force at all to make the wheels spin in opposite directions, it will do it on its own with the wheels in the air and you spin a single wheel.