4T MOTOR LUBRICANTS
The vast majority of modern motorcycles use the same oil to lubricate the engine, transmission, and the clutch. Motor oil lubricates moving parts by covering these parts with a slick film. Oil’s ability of resistance to flow is called viscosity. When motor oil is cooled, the viscosity of the oil is thick and is capable of producing a friction-resistant coating on surfaces. As internal engine temperature rises, the viscosity thins out, allowing the oil to flow better, but reduces the tendency to adhere to the parts. The viscosity index measures the performance of an oil’s viscosity changes as engine temperatures change. A higher viscosity index indicates that the rating of the oil’s viscosity, changing less in high-temperature
situations than a lower viscosity indexed oil.