Auto rust is a common problem for people who live in moist, salty environments, typically people who live near the beach. Nonetheless, auto rust can affect all cars in all environments. First, identify the problem areas, and then select a rust-fighting technique.
Despite car manufacturers' efforts to eliminate it, cars still have rust. The most problematic areas are the engine and trunk compartments; the frame and chassis (the underbelly of the car); and painted surfaces. Rust occurs with moisture, so in the engine, rust can occur near any intake systems or where there may be leaks.
The chassis and frame house the exhaust system, which will develop substantial amounts of moisture. Also keep an eye out for any areas with hinges that can "trap moisture," increasing the likelihood of rust. Finally, paint endures much of the weather and the metal underneath will rust as paint chips away.
Inspect your car for rust or fractures in protective coating, like paint. This can prevent rust from causing severe structural damage. Additionally, protect your car by applying a VpCI (vapor corrosion inhibitor) to exposed metal parts. Finally, if you do detect rust, act aggressively to prevent it from spreading further.
The best solution to eliminate rust, albeit the most expensive, is to replace the rusted metal part, assuming the part can be removed. Alternatively, you can obtain a "rust converter," a solution that creates a chemical reaction that halts the rusting process. Make sure that the area you "convert" is completely dry. Rust converters tend to trap moisture, making the rust worse.
For areas that are difficult to reach but have minimal exposure to weather, use rust-slowing agents. These tend to be much easier to apply than a rust converter and will slow or even stop the rusting.
Finally, if the rust spot is on the exterior of your car, sand the exposed area and apply a primer, and add layers of paint. The key is to allow the paint to dry overnight and then apply several layers to the rusted spot.
