Ever wonder why you need to have your oil changed? Your car functions properly because all of the many parts of the car are working together. Without all of the parts doing what they're supposed to, your vehicle won't work like it's supposed to.
Many of the parts of your car don't even touch each other. Instead, they are riding on a thin layer of oil. Oil keeps all of these moving parts separated and prevents friction and damage of those parts. Oil also circulates and cools parts of your car...