David wrote: >Unless the oil is VERY old and completly black modern oils have a very high capacity to hold dirt and moisture.< He forgot to mention acids! Both acids and moisture in an engine will start rust and corrosion during long term storage. The oil will sooner or later drain off of the cylinder walls, cam lobes, etc., that will then rapidly be attacked with any remaining water and acidic moisture. > I change the oil in the spring along with the filter after a good warm-up. < Personnaly I don't think many engine or oil experts will agree with that schedule. My recommendation, used over a number of years in both car and airplane engines that are put away for winter storage: - Run the engine for a few minutes after it has reached normal oil temperature. - Drain oil completly and replace oil filter. - Fill up with new oil (not colder than room temperature). - If you want to be extra careful, pull the spark plugs and squirt some oil into the cylinders, then crank the engine a few turns and replace the plugs. When spring finally rolls around: - Run engine until warm. - Drain oil, replace the filter and fill up with new oil, then drive it until it reaches normal operating temperature. Check to make sure no oil seals have given up the ghost during storage. There are more things that can be done if you REALLY want to "pickle" the engine but this should suffice for normal winter storage. Roger [Non-text portions of this message have been removed]