Developing Efficient Motorcycle Oils

Motorcycle OEMs faced with stringent global fuel economy and emission regulations are being forced to develop new hardware and emissions control technologies to remain compliant. Motorcycle oils have become an enabling technology for the development of smaller, more efficient engines operating at higher power density. Many OEMs have therefore become reliant on lubricants to not only provide enhanced durability under more extreme operating conditions, but to also provide fuel economy benefits through reduced energy losses. Unlike passenger car oils that only lubricate the engine, motorcycle oils must lubricate both the engine and the drive train. These additional requirements place different performance demands versus a crankcase lubricant. The drive train includes highly loaded gears that are exposed to high pressures, in turn requiring higher levels of oil film strength and antiwear system durability. Wet starter and drive clutches require specific oil friction profiles for good operation and durability. These friction requirements render wet clutches sensitive to friction reducing additives that would typically be used to improve fuel economy in passenger car oils. The formulating complexity for such shared lubricant applications can be further compounded by a need to deliver these higher levels of performance while complying with physical and elemental restrictions to ensure compatibility with the latest emissions control systems. In this study, the development of emission control system compatible motorcycle oils having improved efficiency while maintaining uncompromised durability will be presented. Performance balance was achieved through a combination of reduced operating viscosity (enabled by enhanced antiwear technology and shear-stable functional polymer technology) in combination with clutch-friendly friction reducing technologies. Significant fuel economy benefits were demonstrated using tribological bench testing in conjunction with proprietary fired motorcycle engine testing. Further proof of real-world fuel economy performance was obtained via chassis dynamometer motorcycle testing using World Motorcycle Test Cycle (WMTC).