Our first trip in our '99 Contessa (a short 100 mile maiden voyage on Hwy 101 up the Oregon coast), I noted that the coolant never reached temperature, and I assumed I had a stuck-open thermostat. But the problem has never occurred again, and we have driven it many trips and 10,000+ miles. So I assume the thermostat was acting sticky from sitting months at the RV dealership without being run. We also changed the coolant after our first year of traveling, just because we don't know when the prior owners might have done that last. I plan on monitoring the coolant via Cat's sample analysis, just like I do with the oil at oil change intervals (I change the oil every 8000 miles or so (when we get back home after each major cross-country trip)).