I have a 95 z with 7,000 miles on it. I recently changec the original diff. fluid with royal purple 75-90 synthetic oil. does anyone know if I still need an additive?

 

I have always been told that you should add it reguardless of what type of oil you put in. Plus it is not very much, when you look at the possible risk of replacing the posi(in the long run if its missing causes the posi to "burn-up").

 

I believe royal purple already has the additive in it, read the bottle.

 

Spend the $4 or $5 it costs. If you don't need it, you'll have some extra oil in your differential. If you do need it, you won't have to worry about it. It's better than listening to that groaning sound from the rear end!

 

yeah your probally right. thanks.