"fxdave".......I think you might be talking about OAT coolant (Organic Acid Technology), not Cat. In your motor home, they originally used an old style coolant that required testing a couple of tomes a year to make sure the DCA's or SCA's were at the proper level.....a real pain. I believe Cat does make a coolant, but OAT coolants are what you're looking for.
The new coaches are using the OAT coolant that comes in several brands. It doesn't require any testing and has a long life.
Draining and refilling your system is pretty easy. The hardest part is getting rid of the old coolant.
I found one of those large round tubs with rope handles works well for draining. Drain out your old coolant and fill with water. Make sure you turn on your heater to get the coolant out of the heater hoses and heater core. Drain again. I like filling it one more time and doing a final drain.
Your cooling system uses coolant and DISTILLED water only. Don't worry about how much your system holds. Most of the new coolant is sold as a 50/50 mix. Buy a gallon of concentrated coolant and add this first. This will mix with the approximately gallon or so of water that can't be drained from the system. Now fill the rest with the 50/50 mix until full.
Run the coach and then recheck to make sure that all air pockets have filled and the coolant level is correct.
Don & Mary
2014 Newmar Dutch Star - All Electric - 450 ISL
2016 GMC Canyon 4WD Crew Cab