I took my MH to a dealer last year to be winterized, they don't use the RV anti freeze.....only air. The line going to the drinking faucet had to be replaced. I don't know...they said the line was old. It cost me about $100.00 for the repair. When I do it, I set the air compressor regulator at 40lbs....I have a adapter I purchased at CW and open the valves one at a time for about 5 mins. Once that's done I add RV anti freeze to the holding tank and have the pump push it thru the system. Then add AF to the traps and black and gray water holding tanks. I live in Wisconsin and never had a problem as long as I add AF to the system.
This makes me sad, it's means my season is almost over.
Happy camping, bye Dennis