"Washing the cylinders down" - What does that mean? Is it unburnt fuel cooling the cylinders walls irregularly or something?
"If the increased quantity of fuel is great enough, it can "wash" the film of oil from the cylinder walls, prior to ignition. This leaves ring-to-cylinder metal on metal, bad business." Also, too much unburnt fuel can get past the rings and mix with your oil. Gas is not a very good lubricant so that would be another bad side effect.