What type of fluid needs to go in the front diff of an XJ with a 242?

What type of fluid needs to go in the front diff of an XJ with a 242? Synthetic?

Any reason an XJ would need 75-140 synthetic with a limited slip additive in the rear, just because it has a tow package?

Do you have the owner's manual for your XJ? If not then you need to get one from Jeep. Just call Techauthority and order one. Also while on the phone order the shop manuals for your vehicle, they will pay for themselves.

You may also want to go to the dealer and get the build sheet to see if you have the limited slip rear differential or someone added a hitch later. Not all XJs with a hitch have a limited slip differential. Do you have a full size spare? If you have a full size spare then you have 99% chance of having a limited slip, if you have the doughnut spare then you don't have the a limited slip differential.

The owner's manual gives you the fluids for each component and the change interval. My 88 XJ says to use Dextron ATF in the AW4 transmission and transfercase - the 231 or 242. Use 75W-90 in the differentials. It also says to use the 80W-140 if you are towing but that would be for the rear differential. This is where the owner's manual is worth it's weight in gold.

Just want to add a data point. I have a 90 Laredo with tow package and full spare without limited slip. Owned it since new so I know its all original. My 92 Limited does have all three.

i use 75w-90...

pete