Friction modifier and limited slip additive, same thing?

[Seraphitia102]

I brought my gears to be installed and the installer asks "where's your friction modifier?" And I pointed to the Royal Purple bottle that it says "contains limited slip additive." He just looks at me and says "We'll find out if it works."

Is "friction modifier" also known as "limited slip" in terms of additives required in the Ford 8.8" rear differential?

 

[DTNODYA]

Don't get too confused. The RP should be just fine ... there are tons of people on this forum that use it in their differentials. When you drive your car, if the rear end 'chatters' then add some friction modifier. You shouldn't need to though. IMO

Mike could tell you for sure.

 

[ADRENLN]

i thought they were the same thing

 

[DTNODYA]

I really don't know. When I changed my diff. fluid, I went to Ford to buy some friction modifier. At the time, I had already bought some synthetic fluid that did not contain friction modifier. The guy at Ford said that the friction modifier would not work with the synthetic fluid. That confused me because of all the stuff I've read on here about RP (though that's not what I had ... I had Mobil 1). Long story short, I ended up using good 'regular' diff. fluid and friction modifier just to be on the safe side. But I've read tons of posts that say to just use RP without friction modifier.

Honestly and somewhat ironically, I trust some members on this forum more than the people at my local Ford dealerships. So all of that is what I based my post on.

 

[Kilgore Trout]

Yes it is the same thing and RP is one of the manufacturers that adds it to the synth diff fluid so you do not have to buy it seperately.

In other words, you will be fine

 

[Seraphitia102]

thanks guys

 

[spederman]

Yeah, i used royal purple when i did mine too. You dont need the friction modifier with royal purple.