I've been considering to change over to synthetic transmission fluid. Is there a drain on the torque converter? Or could you change the fluid a number of times to complete the change over. The Synthetic Companies state the fluids are compatable. I was considering REDLINE Transmission Fluid vs Amsoil or Mobil 1. The car is a 85 635 EURO with 92k, I recently changed over to MOBIL 1 motor oil. Thanks for any help in this matter.