rear differential additive

[ca1119]

Do I need to add the additive if I use synthetic differential oil? I was told that the additive is not needed with the synthetic oil.

[GM-Tech]

Do not use the additive in trucks with synthetic fluid.

[fossil]

If your using GM synthetic gear lube don't use it.

If your using anything else use it. I changed mine and didn't use the GM gear oil. My lsd diff ended up being untill I put in some additive.