I have had a Honda 21" Lawnmower for about 15 years. I usually change the oil with 10W30 once per year using the drain plug on the bottom of the engine. This used to be a real pain, as you have to scrap away the grass from the bottom, and remove the drain plug to drain the old oil into a pan, and the pan would get full of dirt and grass. I now just remove the dipstick, and tilt the mower 90 degrees onto it's side. The used oil drains right into the drain pan, and it comes all out. No mess, no drain plugs, all in about 60 seconds.