Extended-Drain Field Testing of Group III-Based Lubricants in Heavy-Duty Transmissions and Axles

In North America, all of the major suppliers of Class 8, heavy-duty manual transmissions and axles offer extended equipment warranties for 1,200,000 kilometers of on-highway service. In order to obtain the extended warranty, the customer must use an OEM-approved lubricant. The initial drain interval of the extended-warranty lubricant is 800,000 kilometers. Each OEM requires the lubricant marketers to pass very demanding bench and field test specifications in order to gain official approval. This paper describes the development and field testing of three extendedwarranty lubricants made with Group III base oils. One lubricant is specially designed for heavy-duty, non-synchromesh manual transmissions. Another lubricant is specially designed for heavy-duty, rear drive axles. The third lubricant is designed as a "one drum" fluid for both transmissions and axles. The bench and field test results show that these lubricants perform as well as the more commonly used Group IV PAO-based lubricants in extended-drain applications.