well environmental issues aside for a moment, the way that i liked was spraying on chainsaw bar oil with a suction gun like you use with buckets of degreaser. i put the oil in a can and put the can on a hotplate to warm it and make it thin enough to spray, but then it thickens up and stays in place, bar and chain oil works best cause its made to be sticky and stay in place, so less environmental issues i suppose. i know its not the best thing, but its about the only way to make a box tube frame like foreign trucks use last the life of the vehicle up here in the north where salt is so heavily used