The gears of an automobile's transmission can create a lot of heat due to friction. This heat is battled using lubricant. Engine lubricant, or gear oil, is used to reduce the coefficient of friction between gears in motion.
The oil pan of a car acts as an oil reservoir. It's a spot for the oil to collect if the engine isn't running. It also is where the oil cools as air passes over the surface of the pan. It's a place for impurities in the oil to settle and it has a drain to allow for removal of old oil.
The oil pan is located directly below the engine's transmission. It bolts directly to the engine and has a gasket to ensure against leakage.
Oil pans are built tough. Usually, they won't need replacing unless some serious damage, such as driving onto a median, occurs. The gasket occasionally requires replacement and as of 2010 one could be purchased for $20 to $40. If the entire pan needs replacement, you could purchase one for around $150 to $250.
