When Should You Change Transmission Fluid and When Not To

1. Should you change transmission fluid if it is burnt or very dark? When should you change it? Silverado and F150. 2. Can you still get parts for a 1994 Ford Taurus to fix the transmission? 3. Why do my Ford dome lights stay on all the time? 4. How to fix hard to fill gas tank on a Jeep Grand Cherokee 5. Why does my 21 Duramax 3.0 Overheat? 6. Why does my Jeep Patriot transmission overheat?