by Robert Sanborn on Wed, Jun 21, 2006, who was a member of the STLE Society of Tribologists and Lubrication Engineers for 15 years.
This question is asked many times and it concerns limited slip differentials or posi-traction.
Due to Gearzol’s extreme pressure agents, adding too much of a good thing could cause slippage; thus SFR recommends using only ONE OUNCE per quart of Gearzol in gear oil for in limited slip differentials. This is because limited slip differentials are made to work on a partial friction basis so that your tires do not just sit and spin when stuck. Gearzol has been tested and used successfully for many years at 1 ounce per quart, but we caution our users not to use more than this ratio. We have this recomendation listed right on the label of all product.