Auto Rust Proofing helps to prevent rust. If you want to try and make your car body last longer, it is a wise idea to apply rust proofing every fall, when the weather get colder, but before the snow falls. It is not just the water on the roads caused by the road salt that rusts your car body and underside out, the road salt in that water does a terrible amount of rust damage to metal work. Applying rust proofing can help prevent or at least minimize or slow down that rust damage, making your car last longer and increasing your resale value of your car or truck.