Rust occurs when oxygen and moisture react with metal to corrode and weaken the surface. If this process continues unabated, it can weaken the metal to a point where it will break. Light cars and trucks, especially older vehicles, are susceptible to rust on their body panels or frame. Repair work can be expensive, and a rusted frame can render a vehicle unsafe to drive. Locating rust spots and treating them before they weaken the vehicle's structural integrity can save you a lot of money in the long run.
Clean any grease, dirt or oil from the rusted surface with an automotive solvent. Allow the area to air dry.
Clean any loose pieces of rust from the area, using sandpaper or a wire brush.
Clean the area again with an automotive solvent. Make sure any loose pieces of rust are removed from the area. Allow the area to air dry.
Apply a rust-converting primer to the area. Follow the instructions on the can for the specific brand you decide to use. The primer will react chemically with the rusted surface, and inhibit rust in the future.
Apply a topcoat to the area if necessary. For areas on the underside of the car or the frame, you may not wish to apply a topcoat. For areas on the outside of the vehicle's body, apply touch-up paint that matches the color of your car.
