The SAE J300 classification was expanded to 0W-12 and 0W-8 viscosity grades in 2015, and lower viscosity engine oils have been studied in the industry. ILSAC GF-6B that will be introduced in 2020 will specify a 0W-16 requirement, but 0W-12 and 0W-8 grades are not considered. Because engine oil equal to or higher than the 0W-20 grade is recommended for almost all engines globally, suitable engine tests for 0W-12 and 0W-8 do not exist. Therefore, the Japan Automobile Manufacturers Association, Petroleum Association of Japan and Society of Automotive Engineers of Japan decided to establish new 0W-12 and 0W-8 low viscosity engine oil specifications. It is referred to as JASO GLV-1, and together with a new fuel economy engine test procedure, these engine oils for better fuel economy will be put on the Japanese market in 2019.
Motoring friction torque tests are widely used to ascertain the friction reduction effect of fuel-economy engine oils. However, the estimated improvement in fuel economy in actual vehicles has not been shown clearly. In this study, a new motoring friction torque test was established for JASO GLV-1. It correlates with the Worldwide Harmonized Light-duty Vehicle Test Cycle (WLTC) that has been adopted in Europe and Japan as the fuel economy certification test mode. Test results obtained with 0W-8 and 0W-16 JASO reference oils show a fuel economy improvement due to low viscosity and the friction reduction effect of the Mo friction modifier. In addition, the correlation between air density in engine bench tests and the measured friction torque was confirmed. A formula is proposed for adjusting the measured torque according to the air density so as to improve motoring test accuracy.