It is a common question from homeowners and equipment operators alike: is heating oil the same as diesel? The two fuels are close relatives. Both are middle distillates refined from crude oil, and No. 2 heating oil and No. 2 diesel have very similar properties. But they are made to different specifications, taxed differently and, in many cases, held to different sulfur limits. Those differences decide where each fuel can legally and safely be used.
Heating oil vs. diesel: the short answer
According to the U.S. Energy Information Administration, heating oil and diesel fuel are closely related petroleum products called distillates. Heating oil is sold mainly for furnaces and boilers, while diesel is sold for engines. Chemically they are similar enough that the main differences come down to:
- Specification. No. 2 heating oil is made to the ASTM D396 fuel oil standard. On-road diesel is made to ASTM D975, the standard for diesel engine fuel.
- Taxes and dye. Heating oil and off-road diesel are not subject to federal highway fuel tax, so they are dyed red. Clear diesel includes road taxes.
- Sulfur content. On-road diesel in the U.S. must be ultra-low sulfur diesel (ULSD), with no more than 15 parts per million of sulfur. Heating oil sulfur limits vary by state.
- Additives. Diesel fuel is treated for engine performance and lubricity. Heating oil is blended for storage stability and clean burning in a burner.
Side-by-side comparison
| No. 2 heating oil | On-road diesel | Off-road (dyed) diesel | |
|---|---|---|---|
| Main use | Home furnaces and boilers | Highway vehicles | Farm, construction and other off-road equipment |
| Standard | ASTM D396 | ASTM D975 | ASTM D975 |
| Color | Dyed red | Clear | Dyed red |
| Federal highway tax | No | Yes | No |
| Legal in on-road vehicles | No | Yes | No |
Can I put diesel in my heating oil tank?
In an emergency, on-road diesel will generally burn in an oil furnace or boiler designed for No. 2 fuel oil, since the fuels are so similar. A few gallons from a gas station can keep the heat on until a delivery arrives. The catch is cost: you pay road taxes you do not need to pay for home heating. If you add fuel to an empty tank, the system may need to be primed or reset, so check with your heating technician, and do not make it a habit. Setting up regular heating oil delivery is cheaper and avoids runouts in the first place.
Can I use heating oil in a diesel truck?
No, not on the road. Using dyed fuel in a highway vehicle is illegal. Federal law sets a penalty of $1,000 or $10 per gallon of dyed fuel involved, whichever is greater, for each violation under 26 U.S. Code 6715, and states can add their own penalties. There are mechanical concerns too. Modern diesel engines and their emissions systems are designed for ultra-low sulfur fuel with the right lubricity additives, and heating oil is not formulated for that purpose.
Off-road equipment is a different story. Tractors, excavators, generators and other off-road machinery can legally run on dyed off-road diesel. Learn more in our guide to off-road diesel: what it is and who can use it.
Where kerosene and No. 1 fuel oil fit in
No. 1 fuel oil and kerosene are lighter distillates than No. 2. They flow better in cold weather, which makes them a good choice for outdoor or above-ground tanks and lines exposed to low temperatures, and they are sometimes blended with No. 2 oil during the coldest months. They generally cost more than No. 2. Kerosene is also the fuel for ventless, non-flue connected kerosene heaters. Dyed kerosene is also sold at Woodford Express stations.
Woodford’s heating fuels
Woodford delivers several home heating fuel options, depending on location:
- No. 2 Fuel Oil that conforms to ASTM D396 specifications, blended and additized for good storage stability and to resist rust deposits
- No. 1 Fuel Oil and kerosene, including a highly refined, low-sulfur 1-K kerosene that meets ASTM D3699 and is recommended for ventless kerosene heaters, available clear and dyed
- Bioheat, a renewable blend of traditional heating oil and biodiesel, in select locations
- Propane for home heating and other household energy needs
For commercial, farm and construction customers, we also supply low-sulfur and high-sulfur diesel, winter blend diesel and off-road diesel. See our full line of fuels.
Planning for winter? Our home heating oil guide covers ordering, tank storage and how to avoid running out during a cold snap.
Frequently asked questions
Is red diesel the same as heating oil?
They are similar and both are dyed red to show that highway taxes were not paid, but they are made to different specifications. Off-road diesel is produced to the diesel engine standard, ASTM D975, while heating oil is made to the fuel oil standard, ASTM D396.
Why is heating oil dyed red?
The dye marks fuel that is exempt from federal highway fuel tax, so enforcement officials can easily spot it if it is used illegally in an on-road vehicle.
Is heating oil cheaper than diesel?
Heating oil is usually less expensive than on-road diesel at the pump, largely because it does not carry highway fuel taxes. Market prices for both move with crude oil and seasonal demand.
Can I use kerosene instead of heating oil?
Many oil furnaces and boilers can burn kerosene or No. 1 fuel oil, and it is often used in outdoor tanks to prevent cold weather problems. Check with your heating technician before switching, since burner settings may need adjustment.
Get dependable heating oil delivery from Woodford
Woodford is a family-owned, third-generation fuel distributor that has delivered fuel to homes and businesses since 1947, with local drivers who know your roads. Heating with propane instead? Review our propane tank safety checklist before winter. Request a heating fuel quote, open an account, or call us at 1-800-927-3688.
