The first tip for repairing auto body rust damage is to sand the rust off the vehicle with sandpaper or an abrasive wheel, notes Popular Mechanics. Next, apply primer and paint the area.
The best way to tackle rust is to prevent it from occurring in the first place. To do this, wash the vehicle regularly to remove road dirt and salt that can cause corrosion on the body. Check drain holes along the rocker panels and along the bottoms of the doors, and keep these areas as dry as possible.
If surface rust appears on the vehicle, sand the spot down to the metal. Apply a primer and paint the area. Finish with a clear coat and blend with the rest of the finish by using a buffer.
If the rust becomes a bubble, the damage is called "scale." To remove scale rust, use a wire brush to remove as much as possible and follow up with a grinding wheel and sandpaper until the surface is smooth. Apply primer, paint and clear coat to the surface.
If rust is allowed to eat completely through the metal, leaving holes in its wake, either cut away the affected part and replace with a new piece or replace the entire panel. Never try to repair a frame that has significant rust damage. This should be done by a qualified repair facility, advises Popular Mechanics.