What if I never changed the oil in my car?

Oil is a necessity that keeps your car lubricated and running smoothly. But what happens if you never change it? And how long can your car really go without having its oil changed?

Oil is an essential lubricant in your engine. It lets metal press against metal without damage. For example, it lubricates the pistons as they move up and down in the cylinders. Without oil, the metal-on-metal… » Full Story on HowStuffWorks