There is this knocking sound when I start the car in the morning. NOt the tick tick or pinging sound. Sounds like the sound when you bang two screw drivers together but louder. It happens like twice until my car is warm and when I turned the car off I heard it once. Anyone have this too? KNow what the problem is?

 

BUMP

 

My Maxima makes the same sound sometimes when I do not drive the car for a few days. It makes a grinding sound (like the timing chain or something) when it starts up. I didn't drive it for a week a couple of weeks ago and it made this noise for <5 minutes idling in the driveway. I drove it around the block and it quit. Anyone else have any ideas? What type of oil is everybody else running? Mine is a '98 with about 57k on it.