I have always done the red pop in my fiver. With the new MH we now have a washing machine and fridge with ice maker.Now the manual says to put the red pop into the drum, I think it said on the spin cy...
On our MH I had to leave the hotwater bypass open for a while in order to get the antifreeze to flow through the incomming water line to the washer. There should be a small instection panel below the washer that you can take off to see if the water lines to the washer turn red. And there are both cold and hot water lines to the washer.