AM-00-26 CHANGING GEAR (The Evolution of Automotive and Commercial Gear Oils Into the 21st Century)

Description:

The evolution of gear lubricants over the past couple of decades has been driven by a desire to improve performance while eliminating cost from the system. The transition of gear oils from those which met the American Petroleum Institute Category (API) GL-5 in the 1980s, through the incorporation of transmission performance and gear cleanliness in the mid-1990s (API MT-1) to those of today which bring significantly higher performance is an interesting study. The gear lubricant formulation changes are a direct result of heavy and light duty vehicle evolution during this time period, and have also been impacted by environmental and political issues. These higher performance fluids bring many advantages over their earlier API GL-5 counterparts. Many of these advantages may have a significant impact on the total cost of the system, such as better seal compatibility (potentially reducing the frequency of seal replacement), fuel economy (through efficiency), greater scoring protection and increased wear protection (reducing mechanical failure under severe applications). Other features such as lower odor, and better limited-slip performance are often regarded as more aesthetic, but still represent marketable enhancements. Gear lubricants have moved from the GL-5 commodity of the 1980s to a premium fluid with performance features demanded by commercial and automotive drivers today. This paper describes this evolution and discusses many performance features for differentiation now enjoyed by lubricant marketers.