I have a '91 XJ that I want to change the front and rear axle fluid in as well as the transfer case fluid. 4.0L engine, and I am pretty sure it's the AW4 automatic trans.

My questions are as follows:

With the AW4, do I have the Chrysler 8.25 rear-end with my XJ?

Front axle is the Dana 30?

I want to see first if the lubricant looks dirty. What are the physical characteristics of "I-need-changed" fluid?

How do I tell if I have limited-slip diffs so I know what gear oil to get?

Thanks for any info guys.

 

yes u have dana30 front,not sure about rear axle,i have the same tranny and i have a dana35,but if its black or real dark then change it

 

I would just change it if you dont know how long its been.
D35 has a rounded case, 8.25 has a flat "lip" on the bottom.

Front is d30

 

I would bet on a Dana 35 rear. You can google the different rearend and get a pic of the diff cover to compare with yours, thats what I did. As far as fluids it never hurts to drain and change the fluids as long as you put back the right fluids.

 

If you don't know then assume it has factory fluid that is 19 years old. Change it.

Once you raise the rear of the vehicle turn on of the tires if the other turns the other way then it is a Open diff.

You also have the AW-4. There are many threads on this forum that discuss what Diffs or on a XJ. A lil search and you will see many examples.

 

 

C8.25 has a rubber plug, dead give away. if you have one of these buy a new fill plug. mine was leaking and I bought a new one from jeep for $3.25.

 

Have you changed it since you bought it? Most owners never change their diff fluids. I change mine once a season atleast. I also change everything as soon as I buy a vehicle

I buy a 20L pale at Walmart for 39.95 of 80w90 gear oil. Works great.

 

No Sir - Absolutely not. My D35 also had a rubber fill plug.
OP, if you have ABS then it's a D35 rear. If no ABS then it's most likely an 8.25, altho I doubt those were available as early as '91. Not sure. As for Limited slip, see above (Post #5).

 

Most early models just came with the turdy5

 

interesting. didnt know a 35 had a rubber plug. ive never seen one.

 

I bought my Jeep about 2 weeks ago, changed out the front diff and tcase oil.
When I looked under my rig to take a peek at the rear diff, there was a tag on one of the lower right-side bolts, it said LIMITED SLIP. I bought some valvoline synthetic 80-90, said limited slip on the bottle, but I also got a few oz. of friction modifier. It's an additive necessary for the limited slip to function properly.

No LSD tag on the front diff, but then again, the previous owner might not have replaced the tag.
Your trans uses dexron III/Mercon V.
If you have part time 4wd, I'm pretty sure the transfer case also uses dexron.

 

gorillaxj, my 8.25 had a threaded metal plug from the factory (mom bought it new in 98). And i know for a fact neither her or my dad changed it out

 

THe whole look at the fill plug thing is a crock.

Just look at the darn cover. That is the easiest.

 

it doesnt matter what they are, go to parts store ...autozone etc.... get some valvoline 75-90w it has additive already for limited slip diffs....if your is open the additive in it will not hurt you open diff......i beleive valvoline 75-90w makes reg oil without the additive too i havent seen it in a while, just make sure its the one with additive if ur not sure, its the same price,and again will not hurt your open diff