What does 5W-40 mean？ Let’s talk about the oil

　 　 [XCAR car original]

　 　 Since buying a car, car owners will enter the stage of car use, and problems related to car maintenance will follow. The first thing to do is to maintain and change the oil. Synthetic engine oil? 5W-40？ Special car oil? A series of questions will come to you non-stop. What? What do you mean you don’t understand? I don’t understand what’s so important about engine oil. Never mind, the editor will have a good talk with you right away, about the oil.

1. What is engine oil?

　 　　This question seems rather trivial, but it is really necessary to explain it. Engine oil, scientific name is engine lubricating oil. As the name implies, it is used to lubricate the engine. If the engine is the heart of the car, then the oil is the blood in the heart, which is very critical. If the engine is short of oil, or the oil is not changed all the year round, it will lead to engine damage or even scrapping. What? It’s not that serious? Let’s take a look at the news that the female driver didn’t know to change the oil for 150 thousand kilometers on the Internet some time ago.

　　　　Anyway, are these black "sludge" in the engine really scared you, so it is necessary to explain what engine oil is.

Second, what is the role of engine oil?

　　　　Engine oil plays an important role in the engine. As long as the engine is running, the engine oil will not stop flowing, and in this flow, it will complete its mission. So what are the main functions of engine oil?

1, lubrication, reduce wear and tear

　　　　Lubricating oil, of course, the first task is lubrication. When the engine is running, high-speed friction will occur on the surfaces of various metal parts. The function of engine oil is to form an oil film between parts through flow, reduce friction resistance and reduce wear, thus prolonging the life of the engine.

2. Cleaning function

　　　　When the engine oil circulates in the engine, it can bring out the carbon deposit, oil stain, sludge and other dirty things produced by the engine, and finally settle in the oil pan to prevent the dirty things from re-entering the engine, thus achieving the cleaning function.

3. Protective effect

　 　　In addition to lubricating the engine, engine oil can also play a protective role through its own "oiliness". For example, engine oil adheres to the surface of metal parts for a long time, so that the metal parts are isolated from the air, which can play a role in rust prevention and oxidation resistance. In addition, the oil adheres to the gap between parts, and the oil film formed can make the parts better sealed and reduce the possibility of leakage.

4. Auxiliary cooling

　　　　With the continuous circulation and flow of the engine in high-speed operation, the engine oil can take out part of the heat in the engine and play an auxiliary cooling role.

5. Buffering effect

　　　　Engine oil can bear part of the impact load transmitted by the bearing, and at the same time, it can also play a certain buffering role for the mutual impact between components.