04 cobra rear diff fluid question

[bird_dog0347]

I need to fill the rear diff (out of an 04 Cobra) and I have two bottles of the Royal Purple 75W-140 with friction modifier additive, do I also need another bottle of friction modifier or is it good with what's already in there?

[terminator03]

just use the royal purple you don't need to add friction modifier to it

[bird_dog0347]

thanks

[Mach1]

just use the royal purple you don't need to add friction modifier to it

Yep

[Baron Von Crowder]

adding the stinky stuff wont hurt either way.