Fuel Efficiency Screening Tests for Automotive Engine Oils

Engine crankcase oils influence automotive fuel efficiency through the energy required to overcome viscous shear and boundary friction. Although the importance of high shear viscosity has been recognised for some time by the oil and automotive industries and suitable viscometric techniques developed for its determination, a less concerted approach has been taken to the measurement of boundary friction. This paper describes two techniques for measuring this parameter to satisfactory levels of accuracy. Based on two commonly-used types of equipment, both methods yield data which correlate well with measured fuel savings.