Normally I winterize my trailer by draining the water from the system and using a hand pump, pumping in RV antifreeze into the lines thru the city water valve, opening the furthest faucet first. Then putting RV antifreeze into each drain. I saw my neighbor at the campground using an air compressor with 30 lbs. pressure blowing the lines out through the city water city water valve. He then put RV antifreeze into each drain line. Is this method as good as putting RV antifreeze into the lines? Thanks, LCP.