Heavy-duty Engine Lubricant Fuel Economy Assessment by Available Test Methods

An investigation of lubricant related fuel economy with two commercially available heavy-duty engine oils was performed using test methods that are currently available to the industry. The SAE J1321 on-highway fuel economy test procedure was utilized in a fleet of four heavy-duty trucks. Fuel economy benefit was defined relative to the CEC RL 191 reference oil that is the baseline candidate reference oil for the European light-duty gasoline engine fuel economy test procedure, CEC L-54-T-96 (Mercedes M111). Fuel economy improvement values were computed from the on-highway test results. Testing the same two lubricants in stationary engine dynamometer tests using the Mercedes M111 and the ASTM Sequence VIB test procedures also served as a crosscheck. Both engine dynamometer tests were found to rank the fuel economy performance of the commercial engine lubricants in the same order relative to RL 191 as did the SAE J1321 procedure. A promising correlation was drawn between the Mercedes M111 and the ASTM Sequence VIB fuel economy results using CEC and ASTM reference oils.