Some years ago, I had an Old Fart friend that had 5+plus acres of all kinds of Diesel motors, trucks, TREASURES and such. In the fall, before the first snowfall, if His timing went off as scheduled, He sprayed used motor oil with a hand-pumped outfit to spray the stuff setting about to help prevent rusting while snowcover was present, untill the spring thaw. He also took an extensive tape of cam-corded footage of everything so he could later locate whatever might be under cover of snow incase He had to locate it. The used oil might work for undercarage??......messy and black, not my best choice. The suggestion of linseed sounds the best to me.