Diff. fluid change question

[FirstFord]

I have a quick question for the pros out there, im changing my rear diff fluid, and replacing it with mobil 1 synthetic, i have used the search, but cant find a clear answer on weather or not to use the limited slip additive??

 

[aldive]

I have used Mobil 1 as well as Amsoil in my rear and have noy used any addative. The truck has 100k mikes now with narra problem.

 

[FirstFord]

thank you for the quick response, so it will not harm my posi??

 

[aldive]

thank you for the quick response, so it will not harm my posi??

I did no harm to mine.

 

[spindlecone]

Or you can use Royal Purple max gear syn, no additive is needed

 

[FirstFord]

I already filled it with mobil 1 seems fine so far.

 

[Brock94]

I just changed mine over to Mobil 1 about a month ago. Per Al's advice, I did not put in the additive and it has been fine.