Diff oil

[Got Smoke?]

can I have some recommendations on different brands of gear lube to use in my diff's that are available at your local... auto zone, advance, car quest, Napa, o'rileys, etc... .



oh I have the factory "anti-slip" so what do I need to look for on the bottle to make sure I don't mess anything up?

 

[Cummins4Life]

I bought some 75-90 Synthetic Valvoline from Shucks not too long ago when I changed mine. Make sure its GL-5 rated, theres and MT-1 rating that has somthing to do with it too. 75-140 if ya tow heavy. Get the limited slip additive from the dealer.

 

[RustyJC]

I bought Royal Purple synthetic at my local NAPA. It has the limited slip differential friction modifier formulated in already - my LSD didn't require any supplemental Mopar friction modifier. YMMV.



The Royal Purple is available in 75W-90 if you don't tow heavy and 85W-140 if you do. We tow a 13,500 lb 5ver and run a GCW of 21,180 lbs (21,500 GCWR), so we use the 85W-140.



Rusty

 

[LSMITH]

Mark, Mobil 1. It is available in any town with more than 1 parts store, reasonably priced and works great. It is fine for your LSD and won't cause any problems, then go to a Dodge dealer and buy ONE bottle of the friction modifier. Add 2 ounces at a time until the chatter stops.

 

[Tom G]

Using Valoline DuraBlend

Changed mine to Valvoline Dura Blend available from Checker Auto Parts. Took exactly 3 quarts for my Dana 80. Since it is a partial synthetic no additive was required for Limited Slip.



Have checked Limited Slip operation and it still works well. Used the 85w-140 since I do tow and dealer recommended this weight. Also temps here in Lake Havasu City are commonly 100+ degrees. Changed mine at 30,000 and it needed it. Will be servicing the differential on an annual basis from now on.

 

[Got Smoke?]

Changed my rear diff tonight... . Valvoline 80W-90 High Peformance Blend meets API GL-5 that my owners manual calls for. A guy I work with gave me some limited slip additive "Trans-X" it meets all OEM requirements... even list's OEM additive part #'s for the "BIG 3" on the front.....



the one thing I'm unsure on right now is I read on here that you should only use 2 ounces of additive, but this Trans-X is a 7oz. bottle and it says to pour the entire bottle in when changing gear lube

 

[Tom G]

Differential Additive

Hi Got Smoke:



If you were using a pure dino gear oil it might take up to 7 oz to stop the clutches from chattering. AND you can sure tell when you need to add it, your rear wheels will be jerky and the inside tire on turns may chirp because the clutches are locking and unlocking. However when you use a blended product like Valvoline very little if ANY additive is required. Adding too much additive can defeat the whole purpose of a limited slip differential.



So how do you tell when you have the right amount? Well the easies way is to just hop in your truck and drive it. Make several tight left and right turns and see what happens. An empty school parking lot or closed supermarket works well for testing. If everything is fine no additive is required. If the wheels are chirping I would try 2 oz. and then go test again.



By now you have probably noticed that the Valvoline product is great. I noticed a big difference in my truck using the DuraBlend product.

 

[LSMITH]

Trans X, I put two 7 oz tubes of that crap in my diff and it make zero difference on the chatter. I drained out the new oil, replaced it and used Mopar additive, half a bottle (4 oz) was all it needed. There are some places where you can save and some where you cannot... ... ...



Listen to Tom on adding it, but buy Mopar, it IS worth the difference.

 

[Dennis Garrett]

in 185k, I've changed the rearend fluid several times. I've also tried several limited slip additives. The only thing that seems to works in my 2500 is the MoPar stuff. No matter what else I use, it will chatter, even if it's supposed to be formulated into the fluid to start with. If you have limited slip, change it every 30k. It gets contaminated with clutch wear material & will ruin the bearings (Eight of them in all) in time. I learned that the hard way.