When changing the rear diff gear oil in a 99 Jeep cherokee,is it need to put friction modifier in also?

the jeep has 86000 miles. what will happen if no friction modifier is added?When changing the rear diff gear oil in a 99 Jeep cherokee,is it need to put friction modifier in also?
If it has ';limited slip';, posi, AWAL, other names pertaining the ability to spin both rear tires at the same time, you will need p/n 4318060AB additive. Your local dealer can run your VIN and tell you if it is built with that.When changing the rear diff gear oil in a 99 Jeep cherokee,is it need to put friction modifier in also?
If you want to know if you have a limited slip rear end, jack both rear tires into the air. Transmission in park or in gear. Try to turn one wheel..If the other wheel turns in the opposite direction, you DO not have limited slip. If it won't turn or you put the jeep in neutral and both turn the same direction, you have limited slip. You do not need the modifier for non limited slip. If you have it, you can do as suggested above and go to the dealer or the additive is available at any good parts store. To answer your question, if you do have limited slip and do not put the additive in, the rear end will make a poping noise as you turn sharply and QUICKLY wear out the clutch packs. While you have it open, look closely at the spider gears for wear.


Good Luck
you should call the dealer and see what they say ..i'm sure if it has a clutch posi in it that it will need a synthetic gear oil or posi lube
You'll need a friction modifier in any of your axles only if you have either a locker, a limited slip or any other differential device other than an open carrier.