I have read on the forum about cabon knock in the N* motor. Indeed, when I bought the car it had some cold carbon knock that pretty much goes away when operating temp. is reached. That knock is still present. I had my oil changed at the dealer 500 miles ago. I noticed today when I rolled the window down at the bank that when the motor is warmed up there is a metallic knock that comes on just above idle under a load. The noise goes away at higher speeds, >1300rpm. If you rev the engine lightly the knock comes and then diminishes as speed stabilizes, and disappears if you let off the gas. At idle, the noise is barely there. Sounds like a rod bearing. My concern, is that the noise seems to be load related. Call me paranoid, some of you might remember my story aboout how the car was returned with a coolant leak, dead battery, and filthy beyond belief. I wonder if the tech drained the oil out and then started the engine without adding new oil. The oil light does not flicker but that doesn't mean anything. I am not going to drive the car until I know more. What do you guys think?