A personal choice. Some just blow out the lines others use the pink stuff. Some so concerned that they do both.
I just blow out the lines because once they are blown out with air you are finished until next winter. When you use the pink stuff you have to flush that junk out in the spring. I just fill my tanks and go. Plus if I use that pink stuff it is a PITA if I want to take my RV out after it is winterized. I can winterize and de-winterize while travelng on the road. I figure I get enough chemicals in my diet just buying groceries and I don't need to add to it.
