I have gas heat now, but in my last house, which was 2300 sq. ft., we had to fill up every month in the winter, with a 250 gallon tank. But, it's much colder here. We keep our heat at 68 and 58 when sleeping. Back then, it was at 58 for most of the day, until I came home from work, when it was programmed to go up to 68.
We also had a "balanced budget" payment, where we paid the same amount each month, agreed to in September. Of course, if the price of oil went down, you were screwed.