not sure if this applies to this Model Year engine, also does the same thing on my 2000 Chevrolet Malibu, currently 192,671 miles and still going. There is a Technicial Service Bulletin (TSB) that I am aware for 2000-01 model year RPO LG8 engine that this is a customer annoyance issue and does not have affect on durability or life of the engine. The TSB states that the noise may be caused by excessive piston to bore clearance during cold engine operation resulting from the specific piston design.
Anything general motors typically has really noisey top ends...period...no need to worry unless it isnt consistent.
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