It is necessary. The engine has been used for a long time, and there is a lot of internal oil pollution, which can easily block the oil passage, resulting in insufficient internal oil supply and lubrication, increased wear, increased fuel consumption, and

carbon deposition

Increase, a bottle of engine cleaning agent, go and see if it is

FAW-Volkswagen

Original trademark, if it is 3M or other series brands such as Bose, It is recommended not to use