Thank you everyone! You provided us with great information - sending us to the Net to search out more info. Certainly enough to know that the coolant in there now (which is a very weak green color) will be flushed out and replaced. We have a CAT dealer close by that we'll be contacting on Monday to discuss their coolant and have located Rotella ELC also.
Thanks for all your support and info as we wade into the mechanical side of our new to us coach!