I am planning on changing out the rear diff fluid on the wifes 02 Explorer. Looking at the owner's manual it states in need to add 4oz of additive friction modifier to the 75W-140 synthetic rear axle lube. Can I get this additive at any auto parts store? Also I plan on using Royal Purple for the diff fluid.

Thanks

 

The lube requirements for the Explorer rear-end are pretty specific and are necessary to have it function correctly and wear as little as possible. I had to have one rebuilt and it cost me about 800 bucks. I wouldn't screw around with them a lot trying new things. If it were my Explorer, I would use a basic, trusted, time-tested , brand of the synthetic gear oil with specs that are called for in the Ford manual for your particular model Explorer, and get the friction modifier directly from Ford. Sometimes just keeping it simple is the best course.

JD

 

Advance Auto and AutoZone sells the positive traction additive that is Ford Spec approved. You only need it if you have a positive tracion unit. RP makes some of the best Rear Diff fluid. I have their 75w140 in my Mustang right now.

 

According to my Vehicle window sticker I have an 3.73 LS Axle. In the owners manual it states to add 4oz of modifier to the lube in LS axles. Not sure if you consider LS, posi?

 

Auto Zone sells a 7 oz tube of the friction modifier. Buy it and put the entire thing in the axle. Dont believe that 4 oz is enough, that is marginal. You can get a good quality FULL SYNTHETIC 75 w 140 gear lube at Wal Mart if your interested. What ever you use, just make sure it is synthetic.

 

The royal purple you are looking at is the right stuff, but get the friction modifier from Ford.