If it is consuming more than a quarter every 300 miles it must be a big leak, check if the oil pan is not cracked or broken, when you stop this leak check if it is still consuming oil, check your exaust fumes color, if it is white or blue means that your engine is burning it, i recomend an engine leak test to know if your rings are ok, if they are ok, you will have a valve seals problem. Good Luck .