Hey Ya'all, I bought a 300 se from a little old Lady that took it back to the MB dealership for everything and from the book I see she changed the transmission fluid every 20 K miles. I am fairly mechanically inclined and I want to keep up the maintenance. How often should you really change the fluid and I have read on here that I need to change all of it, not just the pan. How many quarts is that and what flavor fluid should I use? Thank you for all your help.