View Full Version : Rear Differential Fluid Change

03-29-2006, 04:45 AM
Hey, I am in the middle of replacing my rear differential fluid with MOBIL 1 SYNTHETIC gear oil. I know for synthetics they recommend the 75w140 which is the one i am going to buy. As for the friction modifier, I get it at the FORD right. How many bottles of the modifier and how much gear oil is required. Please in american system of measurements. You know QUARTS and GALLONS.

03-29-2006, 04:56 AM
I'd try 1/2 ounce of friction modifier (half a bottle), and up to the fill line with lube. But dont quote me on that, I've also heard of people just soaking the little clutch packs with the friction stuff.

Joisey Jim
03-29-2006, 10:38 AM
I believe the spec.calls for as much as 4 ozs of friction modifier, but most people I've spoken to say add 2 ozs to start with. The total diff. capacity however, is just over 3 pints (not beer); so you'll need to buy 2 quarts. If you are using 75w140 synthetic, then I'd get the Redline 'synthetic' friction modifier and not the regular Ford stuff.