In recent years, with the rapid development of science and technology, with the wide use of new materials, new technology and new technology, the design and manufacturing level of automobile has been greatly improved, the detection and diagnosis technology of automobile failure is becoming mature, and the automobile maintenance technology is constantly updated. However, people's understanding is lagging behind the development of science and technology. There is a great influence on the residual common sense misunderstandings in automobile maintenance. The main manifestations are as follows: in the maintenance of wheels, a small number of private owners apply the bolts and nuts to lubricating oil in order to prevent the bolts and nuts on the wheels. Knowing this method is not only wrong, but also brings some hidden danger to traffic safety. The bolts and nuts are self locked after tightening. When lubricating oil is applied, the self-locking coefficient between the two decreases and the self-locking performance decreases. When the vehicle is running at high speed, the bolt nut is easy to loose or even fall off, thus causing a traffic accident. In the summer, private owners can wash their bodies with water and wipe them with a rag. It is here to remind private owners that the interior of the body should not be washed directly with water. Because the floor under the floor of the driver's cabin is not "flat and flat". The structure needs to make the floor of the cab floor cushion with many holes and through holes. After rinsing with water, it is not easy to dry in the groove, and it will rust on the gearbox and other parts from the through-hole. In particular, cars with better sealing performance can not wash the body directly with water. The right way is to wipe with wet cloth, but avoid stagnant water. Everyone knows that when the engine coolant is not enough, it should be added in time. But do you use different brands of coolant together? If so, advise you to release the coolant as early as possible and add the same brand coolant again. Because the chemical properties of different brands of coolants may vary greatly, such as effective preservatives for black metals, they often have a corrosive effect on aluminum products, while the preservatives suitable for aluminum gold are harmful to the ferroalloys. Because different brands of coolant are used in different preservatives, they can not be mixed. It is the habit of many drivers to step on the accelerator before starting the engine, especially when the cold car starts in winter. However, this method does not apply to EFI saloon cars. Unlike the ordinary carburetor engine, the engine equipped with an electronic control injection device can automatically adjust the fuel supply according to the engine's temperature and working conditions and make the engine start smoothly. In other words, the fuel injection control device can automatically increase the fuel supply when the cold car starts. Therefore, when the engine is started, there is no need to step on the accelerator, so do not step on it before starting. Otherwise, the engine will not start well.