WD40 is a decent idea for cleaning a lightly dusty chain, but the way my chains get in the winter, I'd need a king sized can every time I cleaned. Even after just a couple of days of riding the chain is literally crusted with gunk. It really needs removing and washing in multiple hot water and soap baths until the baths don't turn black when the chain is put in, then I shake dry and WD40. Then when that dries, a very light oil.

In the summer I can get away with a WD40 hosedown, dry, and oil.