If you run out of engine oil, your engine will fail. Inside of the engine, there are fast moving parts, with a lot of potential friction. The engine oil is the lubricant that keeps parts sliding against each other smoothly, instead of grinding each other down. read more
If you run out of engine oil, your engine will seize almost instantly. However you should get a low oil level indicator light (if your car comes equipped with it), or a low oil pressure light well before you run out of oil. If you get any of these lights you must pull over immediately and shut off your engine. read more
When you run out of oil, friction between cylinder and its container increases a lot, causing high wear. When car runs without oil, friction between cylinder and its container generates a lot of heat, causing further cylinder wear. read more