Oil acts as a lubricant in the engine of a car. Having the correct amount of oil is important for having a car run at its best. If the oil is too low, there will not be enough lubricant and an engine can burn out quickly. Too much oil can have a similar effect, as the overflow of oil will be whipped into a foam by the crankshaft and leak into other parts of the engine, and it can also lead to low oil pressure. Both outcomes can result in major and expensive repairs being necessary for the car. There are a few good ways to double check that the proper amount of oil is in the car.
Warm the engine by driving the car a few miles. Proper engine warmth is important to accurately read the amount of oil, as oil expands as it warms. If oil is filled in a car that is cool, once it warms the oil will expand and cause overflow.