Ruiteng damage assessment consultation

Know when you refuel yourself. If you have been refueling at regular gas stations, there is no problem of inferior oil. The three-way catalytic converter won't break down so quickly. I haven't changed it since the last car ran 200 thousand. It's not up to any expert to decide whether it's good or not. You can measure the exhaust gas, and it is ok if it does not exceed the standard. I suggest you don't have to change. Besides, you don't have any symptoms, and mine doesn't work sometimes.