I'm getting ready to change the gear oil in the differentials front and rear and I could use some help.

I have a 2010 JKU Sahara on 33"Duratracs. I'm 99% sure i have the tow package.

I'm reading I should use 75-140 in the rear, and 75-90 up front. Is this correct?

My next question is do I need the gear oil with the limited slip additive? And if I do, does it go in the rear only?

Last one, should I pull the covers, clean everything and reseal, or just drain and refill using the plugs?

 

I use royal purple but I have a locker in the rear. royal purple works really well for me I don't have to add any additives and I would just change it don't open up your covers.

 

Last time I used the stuff from the dealer, next time I will use Royal Purple. I would just drain and refill. I think the heavier oil in the rear is only for if you do a lot of towing. I don't do a whole bunch of towing, and when I do it is a fairly light trailer, so I use the same oil front and rear.

You only need the additive if you have limited slip differentials. I have lockers, so no additive. If you use Royal Purple I don't think you need the additive either way (I'd have to check their website, but I'm 95% certain that is the case). I believe the factory calls for 80-90. Royal Purple is 75-90, I've never heard of anyone having issues running 75-90, so that is my plan.

 

Is ESP and limited slip the same thing? Trying to figure out if I have limited slip without jacking the jeep up and trying to spin the tires

 

ESP is the computer, a limited slip is a chunk of metal inside the diff. Your build sheet should indicate if you have one. If you don't have the build sheet, go to jeep.com, for owners area, find the contact us link, fill in your info, including the VIN, and ask for a build sheet.

The additive will depend on what you have. Many synth lubes come with it mixed in, so you will not need to add more if you go that route. And as far as I know, a limited has never been offered in the JK front axles, so it will be rear only - if you have one.

For the oil weight, pull out your owners manual and check. The 140 is generally for the rear diff, and just for heavy towing/heavy offroad. But double check the book. Again, if you don't have it, jeep.com, for owners ...

It isn't a bad idea to pull the covers to clean out the insides and give everything a good looking over. But no, you don't have to - as long as you don't notice some indication in the oil coming out that there is an issue. And pay attention to what is on the magnet on the plugs.

 

I checked my build sheet, no mention of limited slip so I guess that answered that.

 

This one is easy, just buy Royal Purple then it doesn't matter what you have, limited slip, locker, open it works with them all. I like to pull the cover if it has much over 50,000 and clean and inspect. Most people including Randy's ring and pinion recommend this as well. As far as the weight people use 75w -90, 80w -90, and 75w -140 and haven't had issues that I've ever seen.

 

I just did this today because I had to replace my pinion seals and didn't trust it otherwise.

From the owners manual:

For the front - Gear & Axle Lubricant (SAE 80W-90) (API GL-5) or equivalent

As for the rear - 226 RBI (Model 44) - MOPAR Gear & Axle Lubricant (SAE 80W-90) (API
GL-5) or equivalent. For trailer towing, use MOPAR Synthetic Gear & Axle
Lubricant (SAE 75W-140) or equivalent. Models equipped with Trac-Lok™
require an additive.

Now if you re-geared, it's all up in the air from there and you'd probably be fine with some 75W-90 or better.

 

If you have the limited slip and you are positive you do. Go to your Jeep dealer parts desk and get yourself a 4 oz bottle of the Jeep Dodge Limited Slip Additive Friction Modifier Lubricant and pour the whole bottle into the diff. Don't waste your time with diff fluid that advertises to have a friction modifier. It's not the same and your rear diff will make some nice ugly noises every time you turn a corner.

 

Running Castrol 80W90 non-synthetic in my Rubi. It has the LSD additive already and have had no problems for thousands of miles. It's also my understanding that Conventional oil (non-synthetic) provides better heat dissipation than synthetic in differentials.