What do you use to treat a cedar fence?

Cedar has natural oils that protect it from insects and rot, it's enemy is moisture and UV. Moisture will make the boards crack and warp, the sun will help with the cracking and will turn the boards grey like drift wood. On a fence grey and cracking are not as much of a problem as on a deck, but if you want to keep your new Cedar fence looking new, paint, dip, or spray the boards with a sealer that has a UV protectorate.