I have a '17 TLX Advance with the (SH-AWD) and the ZF 9 speed transmission, I currently have 106k on the car. The transmission seems sluggish tat times when I first hit the gas, but otherwise preforms slowly. I recently inquired at a repair shop about doing a transmission fluid flush, and they said if it's never been done previously with the current mileage, it can cause more harm than good. I have only had the car for about 6 months and don't see in the history where transmission flush has ever been performed. My question is, does what guy told me about it doing more harm than good accurate? TIA!