does it really make a difference?

i have the fill plug off and it's a little over full

i was going to use some 80w90 for it, but the tag in the fill bolt says
"use special limited slip differential oil"

what does everyone else run?
is 80w90 safe for it?
it's an 87 GXL

 

If u have an LSD u need to use specia lsd oil.

If u have an open diff u need to put normal 80w90 oil in it.

If u put normal oil into an lsd the lsd wont work.

 

thanks for clearing that up.

 

sorry for stealing your post for a sec but where is that writing located, i been trying to find out if my rx7 has lsd and dont want to lift it and spin tire to find out.

 

The above statement is false, it is actually quite the opposite. LSD additive, (whether it is already in the oil such as Royal Purple, or you buy it separately and add it in such as amsoil), helps eliminate chatter, but effectively promotes less lockup of the LSD. Meaning additives do not help your LSD work better. They do however eliminate noise and chatter especially while cornering which is why additives are a must in new LSDs.

So basically if you have a worn and tired clutch type LSD like most FC owners who put in S4 LSDs into their non LSD car, you will get better performance out of it by using little or no additive at all.