Just a note - with this new convenience center or docking station or whatever it's called, there are a few lines that don't get antifreeze as I believe Mudchief pointed out to me a couple of years ago.
On this 2007, I end up using both compressed air and antifreeze. I always start by draining the HW tank and freshwater tank, then connect a 30psi air to the city connect with a valved adapter.
- With the bypass off and anode rod out, I open the air valve and the first shot of air cleans out the HW bypass line.
- Incidently - by performing the step above, I just blew out the city connect to to the pump check valve, so I will not have to risk messing with that little pin to drain it.
- Then, I turn the bypass valve on and open the tank fill valve. The next shot of air through the adapter blows out the tank fill line without contaminating the freshwater tank with antifreeze (a real buggar to flush out).
- I then remove the air adapter fom the city connect and re-connect it to the black tank flush and give it a shot to blow out the flush line (theoretically it shouldn't hold water with the air-gap backflow preventor at the top, but I'm anal retentive)
- All done with the air and ready for the antifreeze cocktail through the antifreeze connection
In the end, the rig is antifreezed, the P-traps are antifreezed, and the initial air blew out the HW tank fill line downstream of the bypass, the tank fill line was blown down, and the city connect line was blown down without any introduction of antifreeze into the HW tank, fresh tank, or even the city connect.
I realize this doesn't help with the Mountaineer or pre-convenience center Montanas, but I think you are better off. My 2003 was just as simple as few gallons of antifreeze and a few minutes of my time. This one take a little more time and concentration.