What Does Viscosity Mean and Its Importance?

How does viscosity affect your engine, mileage and performance?

Motor oil viscosity is the measure of its resistance to flow. Low-viscosity oil (e.g. 0W-20) flows faster than high-viscosity oil (e.g. 20W-50).

To illustrate, think of water and honey. When poured from a container, water flows much faster than honey.

For more good information on oil viscosity including easy to understand charts, read this blog:

What Does Viscosity Mean (and How Does it Affect Your Engine)?