Drain the water tanks. Drain the waste tanks. Drain the hot water heater. Lots of people then suck RV anti-freeze thru all the water lines so they won't freeze. I installed a compressed air fitting in my system so i can just blow it out. Most water heaters have a set of diversion lines at the input and output so you can turn two valves and get the compressed air thru the hot water lines without going thru the water heater tank. I think the anti-freeze leaves a bad taste in the lines. Then put RV anti-freeze in the sink traps. Takes me less than half an hour to do that on our camper.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13