Vehicle manufacturers recommend changing the oil in your vehicle after a certain number of miles or a certain amount of time because the benefits of doing so are very real. Change the oil according to manufacturer recommendations and your engine will definitely see a longer, happier life.
Oil changes are an extremely important part of maintaining your vehicle. After a while, oil breaks down in viscosity, or general thickness, and loses its ability to effectively lubricate the engine.
As well as losing viscosity, over time the oil can collect tiny metal shavings that eventually either clog up the oil filter or continue to circulate through the engine, marring cylinder walls and other components.
Old, contaminated oil may also plug up the screen on the oil pump, reducing its integrity.