Mel-
Our instructions say to simply add two cups of pink antifreeze in the drum and run a spin cycle (1-2 minutes), and of course I drain the WD supply lines with the rest on the plumbing manifold, and it's worked for me for 6 years. But some people do more, and there is a procedure in my instructions specific to the WD if I am pumping antifreeze to winterize the entire coach plumbing system; it's a little more involved, so I simply take the easier first-mentioned approach. It may depend on your WD model, so consult the manufacturer's website or call them.
If your mfr. is Splendide, Phone:1-800-356-0766
Website: www.splendide.com
Service Email: service@splendide.com
-Joel
