posi trac fluid
THis is from torsen's website.
Can Torsen recommend an oil for my rear axle?
We suggest that you follow what is listed in your vehicle's owners manual. We do require that a GL4/GL5 class oil be used for the Torsen T-1. The T-1 requires an oil with extreme pressure additives for optimal function. Torsen works well in either synthetic or mineral base oils!
Is it true that the Torsen unit in the production Camaro needs the GM modifier added?
GM issued a technical bulletin adding modifier to the rear axle oil. This was done to quiet what we call a "Rusty Screw" noise that we heard in a very small percentage of vehicles. This does not happen in all cases, however to address owner's concerns we asked that the modifier be used in all instances to insure that the driver would not get this noise. When replacing the fluid it is at the owner's discretion whether or not to add the modifier. Elimination of the modifier does not affect durability of the differential.
http://www.torsen.com/general/genera...%20rear%20axle
Good luck.



