The most probable reason is that the rings are starting to wear. An engine which develops its horsepower at high revolutions per minute will cause the oil to break down very quickly. Oil that does not look dirty can be shot, because it no longer has lubricating abilities. For smaller engines, an oil change no less frequently than every 3,000 miles is imperative, if you want the engine to last. Unless, of course, you are using a synthetic oil, which has a much different lifespan. That varies from one manufacturer to another, so check with them.
engine burning oil
You are burning oil.
Burning oil
burning oil
chemical
YOUR OIL IS BURNING so check the oil if thats not it check the carbarator
The engine is burning oil.
burning oil causes bonds to break between the oil's molecules which releases energy
Burning oil in a Toyota Camry can be caused by a manufacturer's defect in the engine's pistons. A worn out valve cover gasket can also cause burning oil.
Blue smoke is burning oil.
Burning of fossil fuels such as coal or oil.
White smoke normally means you are burning oil.