The oil you picked will be just fine. It covers GL4 and GL5 spec and you should be needing GL5.
You can always use the "limited slip" additive in your non limited slip differential, but you dont want to be caught not using it in a limited slip diff. The G80 locker doesn't have clutches that need the friction modifier, but those same friction modifiers also will help the pawl that locks the G80 moving easily so that it works properly. It is not needed, but it doesn't hurt.
You can always use the "limited slip" additive in your non limited slip differential, but you dont want to be caught not using it in a limited slip diff. The G80 locker doesn't have clutches that need the friction modifier, but those same friction modifiers also will help the pawl that locks the G80 moving easily so that it works properly. It is not needed, but it doesn't hurt.