Thanks all. It's parked in a garage with a dirt floor, and in the winter it does build up frost on the outside of the coach, to the point it will obscure the windshield enough I have to scrape it. However I have never found frost inside. Am I still OK not using anything, or would that frost potentially build up inside the tank as well? I keep the tank full to the top.
This will be my second year and I did not have any issues last year so I'm all for "if it ain't broke don't fix it" but I have hear about how tough it is to get rid of.