Factory Limited Slip - Synthetic AND Friction Modifier?

[PsRumors]

Changing the gear oil in the rear axle which has a factory limited slip unit. I am using Valvoline synthetic 75w-140 ( http://www.autozone.com/autozone/ac...hetic-gear-oil/_/N-255s?itemIdentifier=977483) which states "Limited Slip" on the bottle.

So is a friction modifier also needed?

My limited slip still works after 16 years and 130k miles. I want it to continue to work after the fluid change. Just don't have the money for a Tru Trac at this time.

 

[Redpower]

I think that is correct. I had to add the friction modifier to the rear end on my F-350 and is not a limited slip rear end. It's not a big deal to do- the stuff is in a tube and you just put it in the fill hole.

 

[onebad7.3]

Do not add the friction modifier

 

[PsRumors]

So we have 1 that says add it and one that says dont.

Who wants to be the tie breaker?

 

[Patrick Feeley]

I added it to mine and didn't seem to have any problems. This is with 75W-140 in the rear end. Cheers!

 

[mudslinger02]

I used the Valvoline 75w-140 in my F-150 just over a year ago, didn't add friction modifier and I've had no problems. And yes it does have limited slip

 

[Peroni]

Valvoline's website for that oil states that it already contains the special additives for reduced chatter.

 

[backwoodsboy]

Don't add it to start. Typically a fluid designed for LS won't need the additive.
Once you have changed the fluid, find a paved parking lot and do figure-8's at moderate speed (~10mph). If you notice chatter then add the friction modifier until the chatter goes away.