There is a rattle noise in engines, when we run it with wrong octane grade (commonly lower than specified), or the ignition timing is not correct, or a higher gear is selected but not corresponding with the vehicle load, speed and/or street angle. This also happens when the engine overheats, the oil is too thin or there is a failing spark plug. The sound is like a metallic and "mute" clank.
Is that called "piston slap"? And where it happens, piston hitting the cylinder walls; where...on top, at the bottom? Or is it the rod bearings; which ones?