Auburn LSD Diff Oil Question

I have a 2018 CM 4x4, and I will be having a local shop install my new Auburn LSD, but I had a question for those who have installed one regarding the diff oil.

The installation manual says non-synthetic 80w-90 diff oil, which is fine. It also says to add GM or Ford friction modifier at a rate of 3 oz. per quart of diff oil.

Our diffs take 3.8 quarts of oil, so that is 11.4 oz. of friction modifier. I don't want to argue with the instructions, but that seems like a lot of friction modifier. Is that what everyone else has put in there?

The LSD in my 1999 F-150 just needed one 4 oz. bottle of friction modifier. Also for those wondering, I am keeping my stock gears because I do not plan on adding bigger tires.

 

It's hard to find gear oil that doesn't already include some sort of "friction modifier". Adding more modifier seems overkill.
Per Auburn FAQ,
https://aftermarket.auburngear.com/general_questions ,
" ... Clutch chatter occurs when the clutch cone engages and disengages rapidly in the differential case. It causes no damage and can be cured by using the correct oil and friction modifies ... "
So you could always start off with little or no extra modifier, and just add more to eliminate any chatter.

 

I used valvoline high performance 80w-90. I got it a pep boys. They do sale a large jug as well. I got an extra quart just Incase.




4 quarts of gear oil and 12oz friction additive. 3oz of additive per quart of oil.

Zero chatter.

 

You can get the additive on line. Any questions you may have have, call auburn directly. They were very cool and answered all of my stupid questions with zero problems. They even tell what companies oils not to use. Oddly enough they said stay away from Locus Oil, for what reason I don’t know. Good luck with your mod.

 

Thanks guys for the insight! Good to know about Lucas, so I’ll go with Valvoline. I just thought 12 oz of friction modifier was a lot, but I guess not!

 

A bit more of insight, the backlash on my truck was .005 my. My friend did the install, he is a master tech/gear specialist for a ford dealership for the last 20 years and was able to get it back to the original spec. He said that Toyota likes a tighter spec than ford and that it is very important to get it back to the original numbers. Thought I menetion this because of the comparison you had mentioned with your f150.

 

I put in a 7oz tube of modifier then filled the diff with 75w90 synthetic, no issues after 9000km (5600mi)

 

The below info is strait from Auburn, for me it makes sense to use what the manufacturer recommends on a product that they developed and tested. To each there own.



Clutch chatter occurs when the clutch cone engages and disengages rapidly in the differential case. It causes no damage and can be cured by using the correct oil and friction modifies. Clutch chatter is caused by the difference between the static (non-slipping) friction coefficient and the dynamic (slipping) friction coefficient. When the difference becomes too great, the clutch cone cycles between the two (sticking and slipping), which creates the noise. Friction modifiers bring the static and dynamic friction coefficients closer together to minimize chatter. Auburn recommends using Auburn limited-slip additive (#504102) with a high-quality non-synthetic 80W 90 hypoid