you must be burning oil as you drive. Do you see smoke at startup? That could be leaky valve guide seals. For good oil consumption, the oil needs to be clean. Sometimes if the oil's dirty enough it gets past the rings and burns in the cylinders. Adding a quart of new oil won't help if the oil's really dirty. the other thing, if the engine's been overheated the rings could be faulty and it would burn oul in the road.