Vsheetz. Sounds like your grandfather was of the same vintage as the painters that taught me the mineral spirits/boiled lindseed oil formula for priming raw wood. Obviously the mineral spirits are in the mix to provide a suspension and penetrant. It evaporates leaving the lindseed oil. You could put the lindseed oil on by itself or cut back on the mineral spirits subject to how you feel it is going on and how deeply you want the lindseed oil to soak into the wood.