Link 03 maintenance needs to do what items, which brand of oil has strong comprehensive ability. The 4S shop recommended me to do a cleaning project. Do I need to do this to maintain?

For people who have walked 30 thousand kilometers, you can do this project or not. If the cleaning effect of the used engine oil is not good, it means that the engine is dirty, and this project needs to be done once. For example, if you choose good engine oil, you can avoid this project. For example, my Maroon 5 engine oil is clean, the engine is not dirty, it can withstand high temperature and has a long mileage, so I don't need to do this engine cleaning project, and there is nothing wrong with the car.