Depends on the particular house. At the moment fuel oil is 3.50/gal and usually 225 gallon tanks in homes. Around $700 per fill up. If the house is well insulated, 2 or maybe 3 fill ups in the 4-5 months of cold. If poorly insulated (or not)… a tank per month.

I’m a navy (submarine) vet myself. But I’m familiar with 2 big jobs in this area related to that field. (Nuc power plant and the shipyard). If you have questions about either of those places. Or other things, lemme know.