Re: Top end engine rattle on start.
There was a major manufacturing problem at the Tonawanda plant at the beginning built of the 09 EcoTec. An additional station and error proofing were added to the head machining line to correct it. Aluminum chips were not getting washed out completely before assembly. A few engines made it past testing and into the assembly plants.
2010 LTZ, White diamond tricoat, sunroof, compact spare, rear 110V outlet, rear window shade, and all the other LTZ goodies. 2.4 EcoTec (My 5th car with an EcoTec)