Rear axle differential question?

Question

97 Mercury Mountaineer 80K mi. AWD traction Loc.

Almost a year trying to figure this problem out.

I've taken this vehicle to several mechanics trying to solve the traction problem that accompanies a low rumble sound from the ear end. The vehicle slips and slides, like fishtailing, at low speeds, and in the rain.

Each time the conclusion was that the differential was fine.

[All new brakes, wheel bearings, 4 new balanced tires, new rear shocks and dampner]

I've been doing some research about the differential and the traction loc axle is supposed to have 4 oz of friction modifier added to the gear oil, and the oil used should be 75X140.

I'm certain that the mechanics have used 80x90 gear oil. Would the weight in oil difference and the lack of friction modifier be causing this problem?

Answer 1

I wouldn't be as concerned with the oil weight as the lack of friction modifier additive.  That could be the root of your problem.

Answer 2

I rather doubt it. the oil you stated was actually 75w140 and 80w90 the 80w90 is better fuel milage wise than the 75w140. the addative is important for the limited slip carrier. I dont suspect the slpping and sliding etc . especially when you say at slow speeds. you see the rear wheels are the main drive wheels and should be barely noticeable from traction lock and not.

www.mycarandineedhelp.com its free and its me  I would like to know more. please give me any details has it been raised , in an accident,change of tire size anything.

Answer 3

Buy 75/140 gear oil and bring it to a mechanic and tell him to put it in. 75/140 is a synthetic gear oil and does not require adding a limited slip additive. Put the correct gear oil in that the factory calls for.