What you are trying to do is prevent the water from freezing onto the steel. I would expect a light coating of grease to work, but don't do more than coat the surface. The grease also gets heavy and could stop the mechanism from releasing.
A light oil or coating is probably better. I would try silicone, as suggested below, or there are a number of more waxy coatings I have used, like the slide out lube for my camper, or some of the anti rust sprays I have seen recommended here.