Rust is the name for iron oxide, which occurs when oxygen comes in contact with iron. The oxygen interacts with the iron on an atomic level, essentially oxidizing the metal and creating rust. When automotive manufacturers roll vehicles off the assembly line, all metal exposed to outside elements have been painted, including the undercarriage. Over time, this paint chips and flakes away because of faults in the original paint job or from damage caused by road hazards during normal daily driving. Preventing undercarriage rust is an ongoing job, especially in areas that use salt for ice control in the winter.
The most important step to maintaining a healthy undercarriage is to take care of it. Wash the undercarriage at least once every couple of weeks in warmer climates to prevent the build up of dirt. In colder climates where salt is used for ice control or in areas where there is a large abundance of saltwater, your vehicle and undercarriage should be washed a minimum of once a week, and more often if possible.
Inspect the undercarriage of the vehicle once a month for any damage to painted areas. Clean any areas where factory paint may have chipped away and cover them with a thick coat of new paint to prevent oxygen from getting to the underlying metal. After washing the vehicle, use a can of black paint or primer and repaint the insides of the wheel wells after they have dried; this not only helps the vehicle look cleaner but helps prevent rust in the wheel wells down the road.
The interior metals of cars, specifically the floorboards and roof areas, often are not painted in detail and are just given a quick basecoat of paint. This makes the floorboards more prone to rusting from the inside out. Keep the inside of the vehicle vacuumed on a regular basis to help prevent the build up of moisture and dirt in the carpeting, and immediately clean up any spills with a wet vacuum.
Undercoating your vehicle is the best way to protect the undercarriage from the elements and rusting. The rubberized undercoating not only seals around the undercarriage, preventing moisture from getting to the floorboards, but acts as a shield against rocks and other road hazards. Rubberized undercoating can be purchased in spray cans that operate similar to spray paint cans that you can apply to the undercarriage yourself. The other option for undercoating is to have a body shop apply undercoating, which normally comes with a guarantee and generally provides better coverage.
