Hope this helps
Think of this way if you burn 1000 gallons of Oil a year, youll need 1400 gallons of propane. Call you local retailer and ask then for the cash price of each. Do the math. Propane compaines know this, that why they recomend it to you. They make more money off of proane. You must always remeber when talking to a SALESMAN they're are in it for them. not you. I dont sell either Oil or Propane just service the products. Dont be duped by the propane "myth".
Brooke Bowen | http://www.reevespropane.com/commercial.htm
Annual maintenance costs. Propane systems less cleaning (although safety inspections are important)
Heating oil tank: You need to factor in the heating oil tanks. Some consumers don't like having a heating oil tank in their basement, nor do they like the idea of potential leaks and clean up costs.
Multiple uses: You can heat your home and run your appliances with propane. Some people don't like having two fuels at there home.
Hope this helps
At the time, the size of the house would not change the answer - oil was cheaper. Size of the house/energy efficiency would affect total cost savings one over the other, but not the answer.
Now this answer may not hold true outside of Maine, where natural gas is common. There is a perception of many people that gas is cheaper than oil which may be true where natural gas prevails. Also, it might be possible that there are some initial costs savings with a gas furnace i.e. you might be able to buy a cheaper gas furnace. But these costs savings would be relatively small and not justify the increased heating costs over the life of the furnace. IMHO.
Sorry can't give you more details - I did not save the calcuations but ran them with our HVAC contractor.. But I believe that oil is the way to go in Maine.