Maintain the car. Maintain what? Why are so many people not in the 4s shop for maintenance?

Maintenance of the owner is mainly to replace the oil filter. The maintenance interval depends on the quality of the oil changed. My car has passed the warranty period, so it is too expensive to change the oil in the 4s shop, and the original oil maintenance cycle is too short, so I didn't maintain it in the 4s shop. I want to go to the garage, but I'm afraid to buy fake engine oil. So I have been buying imported engine oil for myself. It is German GT Maroon 5, a high-end four-grade PAO base oil. Its durability is very good, 15000 km can be changed, and the power attenuation speed is relatively slow. You can only feel the power decay when you run more than 10 thousand kilometers.