There seems to be two ways to winterize. One is to fill the engine from the flush port with antifreeze. This worrys me since it will dilute with the water in the engine.Is a gallon really enough? The manual doesn't say anything about this but says to blow out the water with compressed air from a plug on the pump. I have tried to find this plug but their crappy picture is no help. I would like to know where this plug is, a picture would be good. The tech manual only has the same info as the user manual for instructions and picture.