Oil plays an important part in a properly running car. The wrong amount of oil, or improper care and maintenance, can adversely impact your car's performance. Your car's oil should be changed every 3,000 miles.
Car engines, when running, generate heat. With the friction created by so many moving pieces, the aluminium and cast iron of your engine can melt. Oil is an important component in lubricating your engine to protect it from the intense heat. If the oil level falls below the "fill" level, the engine won't be able to take it up.
Low oil levels can cause the engine to seize, or not turn over. An engine seizing because of no oil often results in the engine being taken apart. Not only can low only levels cause a car to not start, but it can also damage the engine.
Most cars have a warning light on the dashboard indicating the oil level. If the low oil pressure warning light is on while the engine is running, stop it immediately. A running engine with no, or low, oil, can damage the engine. Low oil pressure, under any circumstances, is often an indicator of a more serious problem.