I believe there are two things that cause rust: Unprotected metal and moisture. Salt accelerates the process. Dirt, dust, etc. trap water (and salt) and hold it close to the metal where it can do the most damage. The older the paint and undercoating the more likely it will have small cracks and chips that will allow the corrosion to start. Ironically frequent washing with water will prolong the life of the vehicle by removing dirt, dust, etc. and keeping moisture traps to a minimum. Obviously drains should be keep clear. I have hot water to an outside spigot and valves so I can mix in cold and to get nice warm wash water. Whenever the temp gets above freezing in winter the vehicles get washed with particular attention to thoroughly rinsing the underside, suspension and wheelwells. Every spring I perform a thorough cleaning wiping all the crud out from under doors, behind weatherstrip lips, doorjambs, wheelwell lips, etc. I have Waxoyl'd the truck and the product seems to work well. Nothing beats keeping it clean. One more tip: Use a sprinkler under the car and move it around every couple of minutes to really rinse out the underside. RT

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