Thank you for the clarification. All dealerships should be using oil that meets the specifications of the vehicle. If the dealership uses an oil that does not meet the specifications of GM it would not be a warranty GM concern necessarily. It would be a dealership concern due to the fact our dealerships are independently owned and operated. GM will certainly work with the customer and dealership towards a resolution. I hope this clears everything up. If you have any questions or concerns, please let us know.
Chevrolet Customer Care