First off there is no such thing as gear only limited slip, you MUST have a friction surface of some kind to make a limited slip or posi work. Can't get around that at all.

The AAM has friction surfaces in the form of 6 brake pads on each side helical gear to bias the torque. Certain gear lubes do not provide the correct friction for the brakes to react smoothly and chatter will occur. Other gear luibes have additives that minimize this. If one chatters with your choice of gear oil then it is perfectly acceptable to add some modifier to promote smooth operation.

A smoother operation of the friction surfaces will promote longer life and better wear characteristics as long as it doesn't make it too slippery.

 

Thanks for all the input guys; always educational