Absolute viscosity — Dynamic viscosity
What is motor oil absolute viscosity?
Absolute viscosity is different than kinematic viscosity. While kinematic viscosity measures how a motor oil flows under gravity, absolute viscosity measures how well a motor oil behaves during cranking and how well it pumps when cold. It’s not a flow test. Instead, it’s a test performed by cranking or pumping the motor oil.
In simple terms, a motor oil that has a higher absolute viscosity would be harder to stir than another motor oil that’s easier to stir at the same temperature. What causes one oil to be harder to stir than another? It’s internal friction.
In other words, Kinematic viscosity is a measure of how oil flows when hot (minimum 100°F). So, when oil is expressed as Xw-XX, the XW is it’s absolute or dynamic viscosity and the XX is its kinematic viscosity.
Posted on by Rick Muscoplat
©, 2020 Rick Muscoplat