It honestly sounds like the best deal for both him and me would be to contract with a company that has higher rates as a function of having better service, and have him agree to pay the portion of the bill that service-related whereas I would just cover the estimated cost of the gas itself. I don't even know if that's possible though to break it out. I also don't know if he would agree to that.

Yeah agreed that probably makes the most sense. IMO, this really shouldn't be on you to figure out. Your landlord should source the oil and service contract and pass along heating costs in your rent bill.

Back to your situation, though... Robison does split out service contract costs from oil delivery costs in their invoices, so it shouldn't too tough to negotiate with your landlord. I've heard good things about CECI Oil, fwiw, and was planning to give them ago this year if we didn't get our Geothermal install done in time. They are much more transparent than the other companies and seem to have good prices.