The choice of modern Langdong engine oil needs to consider two aspects. One is the brand of engine oil: 1, the car is 10W-40, and the other is the grade of engine oil. Please carefully check the oil grade used in your car and choose it strictly according to the regulations. 2, the choice of engine oil brand, must take into account the regional environmental temperature. The area south of the Yangtze River can use 10- 15W-40 engine oil all the year round; 3. In Northeast China, choose 10- 15W-40 engine oil in summer and 0-5W-30 or 40 engine oil in winter; 4. The smaller the viscosity of engine oil, the thinner the engine oil and the greater the mechanical wear. The purpose of low viscosity of engine oil is to facilitate starting. After the engine starting temperature comes up, it is still good for machines with high viscosity! Therefore, under the condition that the engine can start normally, the greater the viscosity of the engine oil, the better; 5. There is a famous saying in our car maintenance: save fuel and save fuel, which is the contradiction of oil selection. When selecting engine oil, we must adhere to the principle of "saving shaft".