Fuel Types and Substitutes

Crude distillation separates a barrel by boiling point. The middle cut is the distillate range, and four labels sit in it: No. 1 fuel oil and kerosene at the lighter end, and No. 2 heating oil and No. 2 diesel at the heavier end. The EIA's glossary defines No. 1 fuel oil as reaching 550 degrees Fahrenheit at its 90 percent recovery point and No. 2 fuel oil 640, which is why No. 1 flows at lower temperatures and No. 2 carries slightly more energy: EIA puts heating oil at 138,500 Btu a gallon, diesel at 137,381 and kerosene at 135,000.

What separates the labels in practice is not the chemistry but the paperwork. Heating oil is sold dyed red and, for the heating use it is meant for, pays only a small federal fee; the same liquid sold untaxed for a road vehicle would trigger penalties that the heating oil versus diesel guide computes. Sulfur limits arrived state by state for heating oil but nationally for road diesel. A fuel sold as kerosene may be the certified 1-K grade or a looser range-oil product, and the Consumer Product Safety Commission's guidance for portable heaters turns on exactly that difference.

A furnace burns Btu, so the fair comparison between fuels is price per million Btu. On that scale the lighter fuel's premium is larger than it looks per gallon: at Maine's October 19, 2026 survey prices, kerosene at $6.99 a gallon was $51.78 per million Btu against $43.45 for heating oil, a 19 percent premium on a gallon price that was 16 percent higher, because a gallon of kerosene carries about 2.5 percent less heat. Maine's own table puts propane at $38.47 on the same day, which shows how far outside the heating oil family cost comparisons can reach.

The same arithmetic applies at the pump. E15 carries slightly less energy per gallon than E10, about 1.7 percent in the EIA heat-content arithmetic used in the E15 guide, so a pump discount only pays if it exceeds that difference. The break-even is a calculation the guide does with stated inputs, and the answer moves with the posted prices of the day.

Each guide names the standard or rule that governs the fuel, quotes the agency's own text, and prices the fuel from a dated series with its identifier. Where the governing standard is behind a paywall, as with the ASTM tables of limits, the guide says so and quotes only the public scope statements, instead of repeating cloud points and pour points from dealer pages. Where no authoritative source exists for a claim, such as a blend ratio for outdoor tanks, the guide leaves the number out.

None of the guides recommends a fuel for any appliance. Equipment approvals, local codes and the manufacturer's manual decide that, and a fuel supplier or installer is the right person to ask before changing the grade in a tank.