You don't have to go to the 4S shop to maintain Audi. When changing the oil in the 4S shop, you must check the whole car. If there is a problem, the maintenance technician will raise it, and the decision is up to him. Changing the oil in the repair shop outside is different. Some have not received professional technical training, and the repaired cars are more complicated, and there is no technical standard for maintenance, which is unsafe.