Need some help with Coolant issue in 2002 Tiffin Allegro

Appreciate all the insight. Have an appointment at a Frieghtliner facility to do it right, flush and refill with the "red" high $ stuff. After reading the responses and my own gut reaction to the situation, I decided to get it done right and by a facility that knows what is required. There is too much at risk for me to be guessing.

Thanks again. Happy Thanksgiving to all of you.

David