I have a 95 trans am with an m6. The guy that had it before me replaced all the fluids about 4 thousand miles ago. He put GM syncromesh in the trans, that I am going to flush out and put dexron III back in. He also said that he put new gear oil, and gasket on the rear end. I am unsure if he put the LS additive in the rear. The LS works great, and both tires hook up well. Would it hurt the rear if there was "too much" LS additive in the rear?