I purchased a 07 lexus gs 350 awd from a private owner about three weeks ago. When I'm commuting to work in the morning when I get to a stop sign or red light it vibrates. After ten or so minutes it levels out but it's at a minimum. It has 160,000 miles on it and I'm not sure if the transmission fluid has ever been drained and filled. I had a mechanic check the motor mounts and other areas that may cause vibration. The mechanic asked about has the transmission fluid ever been drained and filled. I told him I don't know. My question is at 160,000 miles is it wise to do a drain and fill. Has anyone else has any information about this situation. Thanks