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How to Substitute Diesel Fuel for Heating Oil

Julie Bawden-Davis
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Substituting diesel fuel for heating oil is possible and safe. Find out how to substitute diesel fuel for heating oil and follow step-by-step instructions for using diesel fuel in your heating system.

If you run out of home heating oil for your furnace, you can use diesel fuel as a temporary replacement. Diesel fuel is available at many gas stations and can be used for a short period of time in most furnaces. Substituting diesel fuel for heating oil will allow you to keep things warm while waiting for your next heating oil delivery.

Diesel fuel and heating oil have a similar makeup. They are both what is known as No. 2 midweight distillations of petroleum. The number indicates the weight and grade of the fuel. That means both fuel types produce about the same amount of heat, and as a result, both can be used in your oil-fired heating system safely.

Diesel Fuel Temporary Fix

There is no limit as to how much diesel fuel you can add to your furnace at one time. However, you don’t want to use diesel in your heating system indefinitely. While running on diesel for a few days is acceptable, continuing to do so could lead to interference in the operation and efficiency of your furnace.

Diesel fuel is not meant for long-term use in your furnace. Your furnace was specifically designed to operate on heating oil, not diesel. Diesel burns slightly hotter than heating oil, which can harm the furnace heating equipment over time. Additionally, using diesel is not cost effective. You will pay significantly more for diesel than for heating oil.

Also keep in mind that while you can use diesel as heating oil in your furnace, substituting heating oil in your vehicle is not recommended. Home heating oil lacks lubrication properties that car engines require to operate.

How to Add Diesel to a Heating Oil Tank

Before adding diesel to your heating oil tank, check that you are definitely out of heating oil. Ensure that your furnace is in good working order and not experiencing a problem, such as a malfunctioning limit switch. Once you determine that your heating oil tank is out of heating oil, you can follow some steps to fill your tank:

  1. You will need a container for the diesel fuel that will hold at least 10 gallons of fuel. Choose a yellow container, which indicates diesel.

  2. Go to the gas station and fill your container with 5 to 10 gallons of fuel. How much you buy will depend on how long you will need substitute fuel.

  3. Turn off your furnace prior to adding diesel to the heating oil tank.

  4. Go to the oil tank’s fill pipe on the exterior of your house and remove the cap. Pour diesel into the fill pipe, which leads to the fuel tank.

  5. Wait 10 minutes before turning the furnace back on. Doing this allows any sediment that was stirred up when you added diesel to the tank to settle. This helps ensure that clean fuel makes its way into the fuel intake line when you turn the heater back on, and the system doesn’t clog.

  6. Turn your heating system back on.

Safety Considerations for Using Diesel

To have success with diesel fuel heating, it’s important to remember that diesel is a temporary heating oil substitute. Additionally, if you keep diesel at home to use if you run out of heating oil, there are some precautions to take. Store the diesel fuel in the correct color container, which is yellow, and clearly label it. Also avoid keeping diesel fuel for longer than six months, as it degrades and can become unsafe. There is an additive that you can put in diesel fuel to prolong its life, but you must use the treated fuel or get rid of it before a year passes.