Kia Cerato 2020 Peace be upon you, guys. May God make you happy. I have transmission fluid that I haven't changed. The car has 350,000 km. I had a vibration from 40 to 70 km/h, and the mechanic told me the torque converter is the issue. He told me to buy a torque converter treatment, drain the pan, and refill the pan with the treatment. After a week, drain it until the fluid is changed. Has anyone encountered this problem before? Please advise. Cerato 2020.