Friction Modifier

[angelo49]

If I use Royal Purple 75-140 or Mobile 75-140, both synthetic,
do you still need to add the friction modifier to it?
I think they both say that they are good for limited slip diff's.
Angelo

 

[coled43]

I used the ford friction modifier (XL-3 I think) on my 2002 because I thought I was having issues with the clutches grabbing. It worked. I had previously changed it out without using it. But if it is for a 2000 2nd Gen explorer, the rear ends are a lot different. I have used the RP in my 99 with no issues and you're right it is supposed to be fine for limited slip. If it is a 2000, I guess you're in the wrong forum.

 

[angelo49]

I knew I forgot something!
2002 xlt tow package 3.73 ls

 

[97awdx]

The friction modifier is a MUST if you have the factory limited slip, 1st, 2nd,3rd or 4th Gen. And it does not matter if it is dino oil or synthetic.

 

[rumpledoll]

I put in Lucas 75W-140 synthetic gear oil in my LS rear diff 2002 V6 Eddie Bauer and the bottle indicated that it already had the friction modifier in the oil. I had a fair amount of chatter with the Lucas, and I found a good deal on Amsoil 75W-140 oil which also indicates that it has the friction modifier in it.

I swapped out the Lucas, put in the Amsoil and also put in 4 oz of the proper friction modifier. No noise at all now. I would say put in the friction modifier even with the RP or M1 oil.

Rumple

If I use Royal Purple 75-140 or Mobile 75-140, both synthetic,
do you still need to add the friction modifier to it?
I think they both say that they are good lor limited slip diff's.
Angelo

 

[angelo49]

I got the Mobil 1 and a 7 oz tube of Transx fm
Somewhere else I read not to use Transx and go to ford and get their fm.
I don't know.

 

[97awdx]

The Ford stuff is supposed to be the best. I have used the TransX without any problems though.

 

[jrey09]

I had my differential with synthetic gear oil service done at the Ford dealership. They originally mentioned that it did not require the friction modifier, but the tech told me he put one bottle anyway. I drove away and felt the shudder about 4 hours later. I went back, the tech couldn't figure out why i had the shudder. he thought it was my tires. finally I went back a third time one week later, they listened to me and after another bottle of friction modifier, the problem is gone.
2002 v6 xlt 2wd 135kmiles