Posts Tagged: oil film

Oil viscosity — Understanding what the numbers mean

Oil viscosity and what the numbers mean A multi-grade motor oil’s viscosity is show with two numbers; a “W” (Winter, not Wax) number which is the oil’s dynamic (absolute) viscosity rating at certain cold temperatures (its cold start performance), and a second number which represents the oil’s kinematic viscosity when it’s heated to 100°C (212°F); its performance when hot. So a multi-grade oil viscosity may be shown as 0W-20, 5W-20, 5W-30, etc. More on Kinematic versus Dynamic viscosity • Kinematic viscosity represents the oil’s internal resistance to flow and shear … Read More