Is there a preferred method to winterizing and why? I have a 5th-wheel that includes a tube and valve to easily get antifreeze to the pump. When I purchased the used RV it had antifreeze in it. I do not know how to winterize and I guess the issue is more the lines than the tanks and mechanisms(pump & heater). I now have an air compressor, so I guess I have the option. Please help this novice as it is getting near time to do it. thanks, John in Pa.