What do motor oil viscosity ratings mean?

Most car owners realize that they need to have regular oil changes to keep their car running well. But what they don't realize is that not all motor oils are the same due to a difference in viscosity. You can think of the difference of high and low viscosity as the difference between syrup and water.
Syrup is a highly viscous liquid while water flows much more quickly and has a lower viscosity. This is the same with oil such as 5W-20. The lower the number the more viscous the motor oil is. The reason there are two numbers…


