1. Sealing strip aging If the sealing strip is not clean, water droplets will penetrate, the door may be frozen in winter, it often happen in north China. Frozen is a very bad solution, good quality seal strip can be easily to solve the problem. As for the bad one, it maybe pay a high price. 2. The paint on the spot Do not wash the car when it is hot, such as a car that has just been driven or exposed to heat, which accelerates the drying process of the cleaning product and water, making washing more difficult and possibly spotting. 3. Paint scratches Sponge circular washing will form a shallow and invisible scratches. Sponges should be moved longitudinally along the hood and other body panels. If the sponge falls to the ground and has not been thoroughly cleaned, it can not be reused, because the sponge may be stained with dirt particles, which will leave scratches on the paint. 4. The wiper motor burns out The best way for wiper when washing the car is leaving the glass, and dry the rubber strip above, otherwise the rubber seal strip and car is easy to stick in a piece of glass, affecting the use. If the wiper switch is turned on during rainy days and the wiper is glued to the windshield, it will burn out the wiper motor. Washing the car is good, but wrong washing process may cause permanent damage to the car. Car wash money is best not to province and choose regular store is necessary.