Engine oil provides needed lubrication for a car engine, and a vehicle can shut down quickly without it. An engine only needs a certain amount, however, and too much can be just as problematic for the car as too little oil.
How Overfilling Happens
The mistake that causes engine oil overfilling involves not paying attention to how much oil goes into a car. Most engines only take four quarts of oil, but there is no exact input gauge. You need to check repeatedly the intake level with the dipstick. Those who don't check frequently can pour in more than necessary.
When engine oil overfill occurs, the engine will hold the extra oil at first. When running the crankcase churns the extra oil, however, it causes it to foam up. Foamed oil won't flow through an oil pump. Then other hot parts subsequently fail to be lubricated properly. Eventuall,y engine failure occurs as an under-lubricated part seizes.
Oil doesn't evaporate. Extra oil needs to be drained out. If you don't know how to do this, take your car to a mechanic and explain the problem. He will drain and reinstall the proper oil level for a charge.