The development of extreme pressure and limited slip automotive gear oils requires care in the selection of base stocks and additives in order to achieve the desired balance of performance properties. Considerations involved in selection of extreme pressure agents, corrosion inhibitors, and friction modifiers are enumerated. Of particular interest is the interference of many corrosion inhibitors and friction modifiers with the desirable gear protection properties. Tests are described for use in evaluating the additives, and performance properties of fully formulated oils are shown. The need for a special lubricant for limited slip axles is described.