For service and parts needs, visit your dealer. You will receive genuine GM parts and GM-trained and supported service people.
Genuine GM parts have one of these marks:

Vehicle Care
California Proposition
65 WarningCylinder Head Cleaning and Inspection (LAF, LEA, or LUK) Engine Block Cylinder Head
Special ToolsEN 22738-BValve Spring TesterEN-28410Gasket RemoverGE 7872Magnetic Base Dial IndicatorFor equivalent regional tools, refer toSpecial Tools.Valve Cleaning and InspectionNote:Do not use a wire brush on any part of the valve stem.Note:Do not grind or condition the intake valve. If the inta ...