I too use to blow out the lines before adding antifreeze. But pink stuff will not mix with water. That's why it looks white or foamy at first. I Use about 5 gallons at minimum. ( two gray and one black tank. No back bathroom ) That's with the washer dryer combo. RV antifreeze is like oil as much as it is antifreeze. Have you ever gotten it on your fingers? You need this lubrication for seals and valves in faucets, toilets etc. put enough in the gray and black tanks to cover the valve. The valve is really what you're protecting. ( that's why there is no need to worry about the fresh tank ) The tanks are just a molded piece of plastic. So even though the valve is on the bottom, it may not be perfectly flat or have the valve as a low point... Even in the summer I have gotten to where there is still a bit of water and all tanks. Just like the toilet seal should never be allowed to dry out.
I don't. But if you wanted to you could reuse the antifreeze because it won't mix with water anyway
Doug2, I have a 15 ROAD GLIDE.