Tank installation + piping + maintenance + exclusive oil supplier, all wrapped up in a 10 year contract attached to the property. I'm not saying there are companies that do that, but I could see it being a possible business model.

Oil tanks + installation are cheap enough I'm not sure it would make financial sense for this to be a business model (we were quoted a ballpark figure of $1,500 to replace ours). Oil tanks require no maintenance whatsoever, just replacement every 15-30 years.

I have an agreement from a company that they deliver oil automatically when I need it, but I don't pay anything extra vs just calling them for a one time delivery and I can terminate the agreement at any time.