The engine should still be under warranty. Insist the problem be identified and corrected. If the dealer refuses to help, ask for a meeting with the district representative. I know from my experience working for a very nice Chrysler dealership, that a representative visits every dealership once per month to handle problems the dealer can't. They have the authority to warranty anything regardless of mileage or time.
Be warned that GM is one of the world's top two least customer-friendly companies so if they refuse to solve the problem, explain that you will not buy another one of their products. A big reason they were hurting financially was a lack of repeat customers. Too many people said "never again". Your word-of-mouth advertising among your friends doesn't seem to be their concern.
GM also has figured out a lot of ways to get your money after the sale. You might consider paying for the repairs yourself, then seeking reimbursement from GM. Be sure the work is done at the dealership. You'll also need documentation. Anything that was done where I worked was kept on file so we could prove the customer really did have a complaint or had service work done in the past. The dealer was the customer's advocate, not adversary. Good dealers want the manufacturer to cover repairs under warranty because it leads to good will and repeat business in the future. GM in particular does not live by that practice.
Be aware too that it is normal for an engine to use a little oil but it should definitely not be running low between changes. For that reason, all manufacturers use "min" and "max" on the dipstick. To prevent complaints from normal usage, they no longer use "add" and "full". As long as the level remains above the "min" mark, no service is required. Since yours is using a lot more, you might try having the oil changed at the dealership, then go back and complain that they must not have filled it completely at your last visit because it is too low. They will either have to add some at no charge or they'll be forced to admit there's a problem.
Monday, August 1st, 2011 AT 7:40 PM