The rear differential cover leakage has gotten pretty bad. Since the truck is in the shop for the new tie rods, think I'll have that done. What exact fluid do I need in order to change the differential out? I know there is an additive I need, but don't know what the part number is. Also, I am stationed in Italy and getting the proper fluid here could be a problem. Our Autoport carries Lucas Lubricant and on the bottle it is stated that you can use it in the differential, anyone have any experience with Lucas?

LT Dan

 

The OE oil is synthetic 75w140 Motorcraft # XY-75w140-QL no other additive is needed as far as I know

 

a limited slip fluid also...u will need.

Friction modifier.....for rear....not needed for front. Rear is synthetic.

 

The "friction modifier" any specifics on that?

LT Dan

 

sorry...dont know the specifics. I thought it was just a general gear friction modifier. ANy rear end place should be able to tell u. I thought I read it in the manual as well?

 

If you can get the royal purple synthetic fluid you do not need to add the modifier, it is mixed in already. Motorcraft brand fluid you will have to add the modifier. I'm about ready to do this myself. I had my pinion seal replaced a few weeks ago and the shop said it looked like there was some water that had gotten in, probably because the seal was leaking. They reccomended that I change the fluid to make sure all of the water was out. I'll be using the royal purple. Rear diff is synthetic, front is not.