Checking your engine oil should be a vital part of your car's regular maintenance schedule. Oil is what keeps the engine running smoothly. If you fail to keep that oil clean and topped off, you will definitely run into engine wear problems in the future.
The general rule of thumb is if it's black, get an oil change. If it's white or mocha coloured, it can be a sign that a blown head gasket is leaking coolant into the cylinders and mixing with the oil. As the engine accumulates mileage, blowly increases. This dump more unburned fuel into the crankcase, which dilutes the oil and causes accelerated wear on engine components such as BEARING and PISTONS, not to mention a loss of performance and fuel economy.