There is several possible reason for the oil consumption but the most probable is the wrong oil was put in at the last oil change . If you put in too heavy an oil it can stick to the cylinder wall and does not get cleaned by the rings and ends up burning off in the cylinder too light an oil can pass through the valve guides and once again be burned off in the combustion chamber. If your PCV valve is plugged it can pressurize the oil pan and also cause the car to burn oil.I would recommend changing the oil and making sure it receives the proper weight oil and also have the PCV valve changed then watch the oil level closely for the next while to see if this helped or if theres a more serious problem like worn rings or valve sets. Hope this helps