antifreeze gone, oil thin

Thank you all. I will fill it up with water and look for leaks, follow the hoses and check the overflow tank for cracks while it's idling. I won't drive it until everything checks out. I will check the tranny fluid. When they put in the new radiator and hoses (30,000 miles ago), is an overflow reservoir part of the package on a radiator replacement? Last ??? I am not sold on the idea of using quite expensive CATERPILLAR Antifreeze from our local dealer. $10.00 gallons of 50/50 Heavy Duty Fleet antifreeze that complies with CAT-EC1 requirements. Made by Command and sold at Truck Parts Store. I shouldn't skimp, CAT says theirs is good for 6 years and the other brands are good for 3. Any opinions on this area I will be facing? Hope the oil analysis goes good Friday. I'll let ya all know. OIL CHANGE, RADIATOR GOES DRY, OIL FEELS THIN. I hope this isn't going to be the norm for Class A Motor-homing. My wife and I had a Living Estate Sale and sold 99% of our possessions and then the house. We're Full Timing it and what a pain when it has to be worked on. Have to find another place to live for the time being. It's late...........