After having checked my oil and it being 2 quarts low (barely registering on the dip stick) I took it to the dealership. They said the cam bearings are worn down. I did a search online and there are a lot of people that have noticed there oil is about 2 quarts low. I'm not sure if it burns it or wasn't full from the factory. GM is repairing my car, but on "good faith" whatecer that means.