kaz2000xjsport

*What to use IN front and rear diff.... I've heard different things, ATF, Gear Oil, etc.. So what do you run in an 8.25 and a dana 30?

bighouts5591

I use 85w-140 gear oil. It's more heavy duty than the recommended 75w-90 for stock, but I have big tires

kaz2000xjsport

yea im changing it when I do my lift so I will too. 33's

EvstaG

Yes definitely gear oil. I run 75-140 as well. And synthetic or dino juice I'm sure both will be fine.

hankthetank

I use 80w90 in some heavy-duty worm gear (read: heavy shear) drives in our roll form plant. A Cherokee with big boots can't come close to the stresses involved there. I use the same in my diffs...guess its just preference. 140 seems a little too viscous for me, you're just creating more heat from friction.

BotakBeng

This is what i'm using...



.......as per FSM.

84zmyfavorite

If you Care about your Cherokee, I would recommend Mobil 1 75w-140 for both front and rear differentials, regardless if its the Dana 30 front High pinion with CAD, High pinion, Low pinion, they All do well with Mobil 1 75w-140. Rear Dana 44s, Dana 35 early(non-Clip) late Dana 35s, Chrylser 8 1/4s All do well with Mobil 1 75w-140 as well. Mobil 1 is EXPENSIVE though, but You Do get what You pay for. If you want to just get by fine with something more Affordable, then I would recommend SuperTech 80w-90 or 85w-140 gear oil. the very thick 85w-140 would be good for a tow vehicles rear diff, or both front and rear diffs if you live where its warm to hot temps all the time.

84zmyfavorite

You will only be able to find 75w-140 gear oil in Synthetic form, by the way. 80w-140 is the thinnest/thickest combo you can find in Conventional gear oil.

kaz2000xjsport

And you just fill it till it starts to drip out the plug right?

Gatchmo5710

Yes

mygreenxj

yep.. i just did my rear diff last week.gonna do front this week if it will stay dry outside. dont know about trans though.mine is a 95 5 speed, i think its atf.

EvstaG

And remember, if your rear diff has the limited slip, you are supposed to add a bottle of the friction modifier in with the oil so the clutches can operate quickly.

And no for the trans its not ATF. You should be running GL-3 or GL-4 grade gear oil. This means that there is no sulfur in it, thus it will not be hard on your brass synchros. Regular gear oil is GL-5 and is not good for these transmissions. I use Redline MT-90 and thoroughly enjoy it.

mygreenxj

where can you pick up the tranny gear oil?

hankthetank

pennzoil synchromesh....napa

salad

Adding to this, most (all?) of the synthetic GL-5 gear lubes I looked at came included with the limited slip additive. Handy for differentials but really don't want that in your transmission.

GL-4 does have sulphur in it as part of the Extreme Pressure additive, however the spec is about half that of GL-5.

Castrol also makes a Synchromesh product. I had to settle for ACDelco Synchromesh stuff which seems to be thinner, nobody in town apparently sells decent fluid for me AX-15 .