do I need to add an modifier to the diff oil when I change it?

thanks

 

Nope you don't need to a modifier to the oil.

 

If you have a VLSD make sure you are using Differential oil not just gear oil... Then you should not have to add any friction additives...

If you have a clutch type LSD, a friction modifier helps keep the noise down...

 

I use the redline 75W90 made for vlsd.

 

stock is VLSD, right?