Going to service my rear diff with 75/90 weight gear oil but do I need a friction modifier?
Thanks

 

I use Amsoil Severe Gear because it contains friction modifiers for the VLSD: https://www.amsoil.com/p/amsoil-seve...gear-lube-svg/

 

THanks! How about Triax Synthetic gear lube, it has friction modifier added to it as well...

 

Have never used the brand, but I see that AutoZone carries Triax gear oil. Any 75W-90 from a reputable brand should be fine.

 

A friction modifier isn't needed for a viscous LSD, as the "viscous" part of the limited slip diff is a sealed unit, and doesn't touch/mix with the diff oil.
They are used in clutch or cone type limited slip diffs.

 

Thanks for the help, first time servicing my rear diff, has low miles for a 2008.....

 

Appreciate the education. I honestly struggle to understand the concept of VLSD since I cut my teeth on cars in the 80s with "posi traction" diffs, which today would equate to a welded differential if I am not mistaken.

What is the lifespan of a VLSD fluid? Can it be replaced? Are there diffs that can replace the one in the RWD sport that are true LSD?