[twindman]

When I boondock, in the mountains it was down to around 30 degrees at night. My furnace runs about 1/2 the time or a little more.
I used the calculation of 1/3 gal per hour a tank only lasts 21 hours, or a little under a day. But I knew I could get more than one day, so then it dawned on me about time running the furnace.
So at half time for 12 hours a day, it would last 3-4 days for one tank. Which is what I get, if I recall correctly.