Hello, the corrosion is mainly caused by the direct contact with the outside world after the metal piece is rubbed. Sometimes accidental scratches, bumps caused by small stones bouncing off the car body while driving, and long-term open-air parking, even the best car will show rust. In addition, the places where the body is prone to water accumulation, such as the inner and outer edges of the wheel arc, the bottom and corners of the door and luggage compartment, are prone to rust after a long time. If the drain at the lower edge of the door is blocked or not very smooth, the water that seeps in when it rains or drives will stay in the door for a long time. After a period of time, it will start to rust from the inside out, and it will be difficult to deal with when it is discovered. Car owners can start from several aspects to keep the car body from rusting, such as keeping the doors and drainage holes in all parts of the car body unblocked as usual. The keyhole of the car door, the periphery of the glass strip and the moving parts of the wiper frame are also easy to rust, and should be wiped with a dry cloth if necessary. Once there are small scratches and rust, the rust should be gently rubbed off with very fine water sandpaper dipped in water, wiped clean, and then coated with a layer of primer to ensure that the rust will not expand and aggravate. If it is a new scratch, it can be cleaned and directly primed. Although this treatment is not beautiful, it is not serious in a small place. In addition, you can also buy a small complementary color pen in a car store. After the primer dries, polish it with water sandpaper and then color it with the complementary color pen. Small scratches or inconspicuous parts can be modified by this method. You can also try toothpaste. If you find a new scratch, apply a little. After raining or washing the car, don't forget to apply it again. It can be simply isolated and will be fine in a short time. But this is just a way to cope. If you have time, it is recommended to go to the repair shop to repaint the paint as soon as possible. Please adopt it. Thank you!