I read the oil analysis page on this site and it said if you have too much copper things to check are strange noise when near stall speed... at low rpms, like 1000 and below, my engine makes a strange noise like a super fast vibration that sounds like the pistons are rattling around in the cylinders, not really but thats what it sounds like, and was wondering if this is the noise that was meant. I have a stick car so i can put it in gear and load the engine down as much as I want in any gear so thats the only reason I hear it...maybe with an auto I wouldnt but just making sure.