Development of JASO GLV-1 0W-8 Low Viscosity Engine Oil for Improving Fuel Efficiency considering Oil Consumption and Engine Wear Performance 2020-01-1423
Hybrid electric vehicles, electric vehicles and other powertrain systems with high energy efficiency are being put on the market mainly in Japan, U.S., Europe and China for the purpose of improving fuel economy. However, vehicles equipped with only a conventional internal combustion engine (ICE) still account for the vast majority of vehicles in use globally. From the standpoint of reducing CO2 emissions, improving the fuel economy of ICEs is still a very important issue.
In recent years, lowering the viscosity of lubricating oils to reduce churning resistance has been actively pursued as a specific approach for improving fuel economy. Toward that end, 0W-16 fuel-saving engine oil has been put on the market. In addition, SAE 12 and SAE 8 were established in the SAE J300 viscosity classification in 2015 as low viscosity grades having viscosity even lower than that of the existing SAE 16 grade. Meanwhile, because SAE 12 and SAE 8 did not have any official quality standards, a standardization study was undertaken at the behest of Japanese vehicle manufacturers, which led to the establishment of the JASO GLV-1 standard by the Japanese Automotive Standards Organization in 2019.
Prior to that, Nissan had conducted a study of a 0W-8 low viscosity, fuel-saving engine oil. Two issues can be cited in connection with lowering engine oil viscosity: (1) lowering the base oil viscosity worsens volatility and increases oil consumption, and (2) wear increases as a result of greater contact at sliding surfaces due to a thinner oil film.
This paper presents the results of a study undertaken to deal with these issues. In order to comply with the JASO GLV-1 standard, the adoption of a gas-to-liquid (GTL) base oil was examined to address the first issue and suppress oil consumption while still lowering the viscosity. For the second issue, optimization of the base oil viscosity was examined along with investigating friction reduction and anti-wear improvement by making effective use of the molybdenum dithiocarbamate (MoDTC) friction modifier.