GEAR OIL DEVELOPMENTS BEYOND GL-5

This paper examines developments/trends beyond the requirements of the API GL-5 category for automotive gear oils. One key development appears to be the establishment of fuel-saving benefits through proper lubricant viscosity and use of friction modifiers. Another development is the trend toward improved durability of the power train from axle to transmission. It is concluded that fuel economy benefits are practical through proper lubricant choice and that GL-5 oils do not necessarily provide improved durability.