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 WarningValve Lifter Cleaning and Inspection
Caution:Refer toValve Lifter Priming Caution.Inspect the stationary hydraulic lash adjuster (SHLA) in thefollowing areas:A plugged oil passage-(1)A scored or worn camshaft follower pivotarea-(2)A damaged or broken retainer-(3), someapplicationsA severely scuffed or worn SHLA body-(4)Replace the SHLA ...