[big gear head]

I've used many different oils with the Eaton Posi, with steel and carbon fiber clutch discs, and didn't have any problems with any of them. I used Amsoil synthetic in probably about 100 of them and it worked great with no additive. Amsoil has changed their oil a few times since then, so I don't know how it works now. I've used about all of the other brands in synthetic and petroleum base and they have all worked fine with the correct additive. I found that the GM and Ford additive work best. I'm giving Lucas a try now and so far so good.

I know that this doesn't apply to you, but Torco oil was the only one that would work in the '06 GTO rear end that I rebuilt. Amsoil only worked for a little while and then it started making a lot of noise. The Torco oil made it quiet again. I would use Torco in any cone type differential, such as the Borg Warner and Auburn.