I have no experience using wax, or silicone, but I'm sure the wax would help. How smooth is the moldboard (blade)? That's the question. If the paint is coming off, and its pitted, then sandblasting it, or using a grinder/wire wheel with new paint would be a good idea as you prepare for next season. The only other option I know would be to purchase a plastic liner that is placed over the moldboard, and then bolted in place. This seems like an elegant solution, as the plastic will never rust, and is pretty slick. I would be interested to hear from anyone that has used one of these. My main concern would be that it might chip, or hold salt laden moisture between it and the steel modboard. Most plow stores carry these, and they run about $60-$80.