Torsen posi lube and additive?

**Ortiz11b** · 08-18-2011, 09:41 PM

Hi there im rebuilding my rear end and droping in a Torsen posi out of a 02 ss with low miles in my car,,, was wondering what gear oil people are using on this style posi and if you still use the additive? i know its not called for but some say it still quiets it down and some say it not good for that style posi... just trying to get a feel for what people use and what to stay away from,, i plan to use mobil 1 / 75w90 and no additive.... thanks

**Knight** · 08-19-2011, 02:14 AM

Clutch style differentials should use the additive, unless the manufacturer has specifically stated not to. Gear or spring style differentials do not require the additive.

Most will run 75w90 or 80w90 gear oil.

**HOBS** · 08-23-2011, 05:47 PM

I've also heard that the Torsen posi doesn't need the the additive. With that said both times I took my T/A to two different dealerships for the rear-end to be worked on they put the additive in. Valvoline makes a gear oil that already has the limited-slip additive in it if you want to go that route.

**pajeff02** · 08-23-2011, 06:15 PM

For whatever reason, the additive is actually recommended in the torsen posi-traction units. I posted on this some time ago -- need a minute to go dig it up.

**pajeff02** · 08-23-2011, 06:25 PM

Here is the quote from Torsen's website: 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.