Mobil 1 Differential Lube for Limited Slip

[wiesjon]

Is there any problem changing from stock lube to Mobil 1 in my limited slip differential. It is time for a change for me and it seems that a synthetic would be much better in winter since it maintains a more constant viscosity. I looked at the bottle of Mobil 1 and it states that it is OK to use in limited slips.

[Genthar]

While the synth is great, you'll still want to add the LSD additive. A number of people have had slippage problems without the LSD additive, despite the fact that the bottle says it's OK for LSDs.

[wiesjon]

Originally posted by Genthar
While the synth is great, you'll still want to add the LSD additive. A number of people have had slippage problems without the LSD additive, despite the fact that the bottle says it's OK for LSDs.

Thanks for the info. I'll definitely get the additive.

[Buzzard]

George at AV Lube says if you buy the Mobil 1 in BULK you have to add the additive. If you buy in quart bottles its already in the fluid---Buzz

[surfratt]

I have always recommended the highest grade rating from the Society of Automotive Engineers (SAE) for ANY gear-oil application. While installing my aftermarket (TRD-Kazuma) Limited Slip Differential (LSD); the documentation called for GS-5 gear oil, along with the additive for the LSD. Look at the top of the can or the side of the plastic bottle and it will tell you the SAE grade. Don't be cheap with any of your gear-oil applications, unless you you drive like Granny and change your oil every time the dealer sends you a letter, which is every two weeks. LOL. IF YOU HAVE LSD, ALWAYS PUT IN THE LSD ADDITIVE; it doesn't hurt to put in additive, but you're screwed if it's called for and you didn't put it in.

[TriTundra]

I replaced mine with Mobile 1 at 20,000 miles and put 7 ounces of additive to the rear end. 2,000 miles later I haven't had a problem. Better safe than sorry.

[lelandstanford]

What's the correct ratio of gear oil/friction modifier per manual?

Originally posted by TriTundra
I replaced mine with Mobile 1 at 20,000 miles and put 7 ounces of additive to the rear end. 2,000 miles later I haven't had a problem. Better safe than sorry.

[TriTundra]

Well, without the LSD the manual calls for 4 qts of oil and with the LSD it calls for 3.3 qts. That is how I fiqured on using 7 ounces of friction modifier. That will bring the fluid level to the bottom of the filler hole. Besides, that is excatly how much was in the tube I bought from Napa.

[lelandstanford]

Here's what I found from http://www.redlineoil.com/products.htm :


RED LINE OIL
Limited-Slip Differential Friction-Modifier/Break-in Additive
TECHNICAL INFORMATION
Red Line Limited-Slip Differential Friction-Modifier/Break-in Additive was developed specifically to address clutch chatter problems of clutch-type, limited-slip differentials. Used in the proper proportion, this product modifies the friction characteristics of the axle lubricant just enough such that clutch chatter is eliminated but proper limited-slip action is preserved.

All Red Line rear axle lubricants except 75W90 NS have this additive in their chemistry. If the perfect limited slip lubricant is desired, fill the axle with 75W90 NS then add just enough Limited-Slip Differential Friction- Modifier/Break-in Additive such that any chatter goes away.

Another use of this product is as a break-in additive for drive axles using hypoid gears. Used in the proper proportions, Red Line Limited-Slip Differential Friction-Modifier/Break-in Additive will significantly reduce the friction between gears during the break-in process of a new drive axle. High temperatures can be encountered during break-in that can damage the hardening of the gear teeth. The softened teeth will, then, rapidly wear to the point of failure. This product can reduce temperatures by as much as 50° F during break-in. Friction Modifier/Break-in Additive is compatible with petroleum-based and synthetic gear lubricants.

This product satisfies the performance requirement of the following manufacturer specifications: GM 1052358, Ford M2C118-A and 19B546-MA, Chrysler 4318060 along with specifications of most foreign manufacturers.

The recommended nominal mixtures are: for drive axle break-in use: 8% of the total lubricant capacity and for normal lubrication of a clutch-type limited slip differential: 4% of the total lubricant capacity.

Your ratio is:

7/ (3.3*32+7)=6.22% is more than 4% recommanded which is on top of what Mobile 1 (non-drum container) already contained.

[wiesjon]

I changed to Mobil 1 rear lube, but without the additive (read on the bottle that is was already OK for limited slip diffs). After driving about 30 miles of in town travel, I noticed a very slight howling whenever I made sharp turns or drove in a complete circle. I went to the dealer, bought 2 - 4oz. bottles of additive (GM by the way) and the howling went away in about 15 minutes of driving). The service rep said they had themselves had to warranty 2 vehicles (replace one rear end and one clutch pack because they themselves had omitted the additive).

[lelandstanford]

While I was change differential oil I had an interesting observation:
Tundra is the first auto trans RWD w/ LSD I own. On all other auto trans RWD w/o LSD, you can easily turn LR wheel and RR wheel will turn in opposite direction (in Park with both R wheels off ground). I use this method to test drag for drum brake adjustment. However, on Tundra it's much harder to turn. Is this the nature of LSD?

[arkie6]

Originally posted by lelandstanford
...On all other auto trans RWD w/o LSD, you can easily turn LR wheel and RR wheel will turn in opposite direction (in Park with both R wheels off ground). I use this method to test drag for drum brake adjustment. However, on Tundra it's much harder to turn. Is this the nature of LSD?

Yes. What you experienced is normal for a clutch type LSD with relatively good clutch discs. You are overcoming the preload friction on the clutch discs and causing the clutch discs to slip. This is the same thing that happens everytime you make a turn in the truck. Another way to check how well your LSD functions is to jack up just one side of the rear end and put the transmission in neutral. Now attempt to spin the one rear wheel that is in the air by hand. On a non-LSD differential, it is fairly easy. On one with a proper functioning LSD, you will encounter some resistance.