Once upon a time, Liquid Wrench was only a penetrating oil to loosen rust-seized nuts. Now it has a full line of purpose-made lubes. Use White Lithium Grease on all moving parts of a trailer to protect from corrosion. It doesn’t run or freeze. For a lighter film, say on a padlock or squeaky hatch hinge, use the Silicone Spray. It goes on clear, leaves waxy residue that doesn’t attract grit and helps remove and prevent rust. The cap holds a spray straw for accurate application. From $6.49; acehardware.com