[JRTJH]

As "different" as it might seem, some people recommend Dawn dishsoap. It coats the ball/hitch surfaces, is easy to wash out or clean up, doesn't stain if you brush against it and provides the needed "slick surface" for metal to metal contact.

I don't use a WD hitch any longer, but did use Ivory dishsoap (pre-Dawn era) years/decades ago.