Guess I just learned something new today. I never heard of oil undercoating before. 
I think my old GMC with the rear main leak could have been considered oil undercoated then! Wish I knew about this before. I could have used it as a selling point instead of something that needed fixin! 
My challenger has developed an intake gasket leak and has managed to coat a significant portion of my firewall in oil. That must be worth an extra 1000 bucks!
Up in the frozen north oil spray is the way to go. I even opt to get the "dripless" one that kinda turns the oil spray into a bit of a sludge that sticks to the metal. Rust proofing oil that drips onto the driveway isn't doing you any good. This method looks ugly but I beleive it works better. My daily driver is a rust free 2008 Hyundai Accent hatch, I need to do everything in my power to stop this thing from rusting.
