Stain colors wood but does not protect the wood. You can buy house and fence stain that will both color and protect the wood. There are transparent stains that will show more of the grain. Oak is open grain so even if painted the grain will show. No clear finish will hold up in the sun and rain. As long as you either garage the truck or plan on refinishing on a regular basis it won't last. This is the information shown on mar-k site.
