I blow out the black tank rinser then do the same with the entire fresh water system. I then pump RV antifreeze to the toilet. Have done this for the past several years without issues. The one year I didn't pump antifreeze I had the toilet valve freeze and crack.
taviking22
Omaha, NE
'06 2500HD Silverado 4X4, Duramax LBZ, Firestone air bags
2008 Tracker Pro Guide V-16 Boat
2012 Jayco Pinnacle 31RLTS