Last Updated February 26, 2026
Refrigerated trailers can keep perishable freight at a safe temperature across hundreds of miles, but their refrigeration systems don’t run on the truck’s main fuel tank. They rely on a separate fuel source: reefer fuel.
Reefer fuel is technically a form of diesel, but it’s taxed differently than standard highway diesel and has a slightly different chemical makeup that makes it ideal for refrigeration.
In this guide, we’ll explain what reefer fuel is, review the key differences between reefer fuel and standard diesel fuel, and discuss the legal considerations every carrier should understand.
Key Takeaways
- Reefer fuel is red dyed off road diesel that powers refrigeration units on temperature controlled trailers, not the truck engine itself.
- Because it is untaxed for highway use, reefer fuel is cheaper than standard diesel but is strictly limited to refrigeration units and other non highway equipment.
- A reefer unit typically burns between 0.4 and 3 gallons per hour, which can add up to 10 to 35 gallons per day depending on temperature settings and operating conditions.
- Misusing reefer fuel in a truck engine is considered tax evasion and can lead to steep federal and state fines, back taxes, and potential legal consequences.
- Strong fuel management practices such as monitoring runtime, keeping detailed records, performing preventive maintenance, and building fuel costs into load pricing help protect margins and ensure compliance.
What Is Reefer Fuel?
Refer fuel is a type of diesel fuel used to power refrigerated truck trailers (commonly known as reefers). These units transport temperature-sensitive freight like food, pharmaceuticals, and certain chemicals, keeping them cold or frozen until they reach their destination.
However, reefer fuel doesn’t power a truck’s engine. Rather, it only powers the refrigeration system attached to the trailer.
Because reefer fuel is off-road diesel, it’s not taxed for highway use. It’s less expensive than standard diesel, but there are strict usage restrictions to ensure people don’t take advantage of the tax exemption. The fuel is dyed red to indicate that it’s untaxed and to help the DOT ensure carriers remain in compliance with reefer fuel regulations.
How Is Reefer Fuel Used?
Reefer fuel is stored in a separate tank attached to a trailer. The red diesel fuel powers the refrigeration unit, which maintains a consistent temperature during transit.
The refrigeration unit runs continuously while there are perishables in the trailer. Because the reefer fuel tank is separate from the truck engine and fuel tank, the unit can run even when the truck engine isn’t running. Reefer units can run for long periods of time, especially when they’re used for long-haul routes, so it’s essential to monitor your reefer fuel usage.
Difference Between Reefer Fuel vs. Regular Diesel Fuel
Although reefer fuel and standard diesel fuel are chemically similar, there are key differences in their tax status and permitted uses.
| Reefer Fuel vs. Diesel | ||
| Feature | Reefer Fuel | Regular Diesel Fuel |
| Color | Dyed red | Clear |
| Tax Status | Untaxed (off-road use) | Taxed for highway use |
| Legal Use | Refrigeration units, certain off-road equipment | Truck engines |
| Cost | Usually cheaper | Higher due to fuel taxes |
How Much Reefer Fuel Does a Reefer Trailer Use?
Reefer fuel consumption depends on several factors, including:
- Outdoor temperature
- Set temperature inside the trailer
- Size of the trailer
- Insulation quality
- Age and condition of the unit
- Continuous vs. start-stop operation
On average, a reefer unit consumes anywhere from 0.4 to 2 or even 3 gallons per hour. This translates to roughly 10 to 35 gallons of diesel fuel in a day, depending on conditions.
On average, a reefer unit consumes anywhere from 0.4 to 2 or even 3 gallons per hour. This translates to roughly 10 to 35 gallons of diesel fuel for refrigerated trailers in a day, depending on conditions.
Where Can You Get Reefer Fuel?
Reefer fuel is usually available at major truck stops and fuel distribution depots. It can also be purchased from designated bulk fuel suppliers across the country.
Because it’s strictly off-road diesel, it’s usually dispensed from pumps labeled “Off-Road Diesel” or “Dyed Diesel.”
If your fleet uses large volumes of reefer trailer fuel, it may be more convenient and cost effective to buy it in bulk and store it at your facility.
Legal and Compliance Reefer Fuel Considerations
Reefer fuel is regulated at both the federal and state levels. Because of its lower cost compared to standard diesel, it can be tempting to use it to fuel your truck’s engine and give yourself a cash flow cushion. However, if you’re caught misusing it (i.e., putting reefer fuel into your truck’s main fuel tank), you’ll face large fines, tax penalties, and legal repercussions.
Off-Road Use Restrictions
Tax-exempt diesel is legally restricted to:
- Refrigeration units
- Off-road construction equipment
- Agricultural machinery
- Other non-highway diesel equipment
Reefer fuel cannot legally be used to power a truck’s engine on public roads because it isn’t taxed for highway use. For example, if you’re using it in a tractor that stays on a farm, it’s absolutely fine, but using it for a farm truck that drives on public roads is illegal.
Penalties for Misuse
Using reefer unit fuel in an on-road vehicle is considered tax evasion. At weigh stations, DOT officers sometimes use a rod to dip in your fuel tank and check for red dye. They can also perform IFTA audits to compare your fuel purchases to total mileage.
Drivers or fleets that are caught misusing reefer fuel can face penalties, including:
- Federal fines of $1,000 or $10 per gallon, whichever is more
- Additional state fines
- Back taxes on the fuel
- Citations
If a driver is repeatedly caught misusing reefer fuel, the legal consequences can quickly escalate to include much higher fines, because authorities see the behavior as continued non-compliance. In extreme cases, it can even result in criminal charges or having vehicles seized.
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Reefer Fuel Documentation and Tax Reporting
Because of the strict reefer fuel regulations, carriers should always maintain proper fuel logs to demonstrate they’re using the fuel legally.
If you face a state or federal audit, incomplete records will cause an unnecessary headache and put you at risk of legal action, even if you didn’t actually misuse reefer fuel.
At a minimum, good records should include:
- Itemized fuel purchase receipts
- Supplier invoices
- Fuel card transaction records
- Reefer unit maintenance logs
- Internal fuel usage tracking reports
Together, these records help prove that you only purchased and used reefer fuel as refrigerated trailer fuel.
Benefits and Drawbacks of Reefer Fuel
Reefer fuel is essential for temperature-controlled carriers, but it comes with tradeoffs. Understanding both the advantages and disadvantages can help you manage risk and be mindful of the associated expenses.
Benefits of Using Reefer Fuel
- Lower cost per gallon: Because it’s untaxed, reefer fuel cost is almost always cheaper than standard diesel.
- Independent operation: Reefer units run separately from the truck engine, so your load stays continuously cool even when your truck engine isn’t running.
- Predictable fuel usage: Once you know what rate your reefer unit consumes fuel at, you can better calculate fuel costs per load and plan accordingly.
- Ensures compliance: Keeping your load at the correct temperature requirements ensures your load won’t be rejected and avoids potential disputes.
Disadvantages of Using Reefer Fuel
- Higher operating costs: Refrigeration units have to run constantly when they’re carrying perishables, so there are always additional fuel costs compared to dry van operations.
- Dual fuel management: Drivers are responsible for monitoring fuel levels, adding another task to their often already full plate.
- Added maintenance requirements: A second, separate fuel system means additional servicing.
- Strict legal requirements: Reefer fuel regulations are rigid, and misuse can result in significant fines and legal penalties.
Best Practices for Managing Reefer Fuel
Understanding your daily reefer fuel usage is part of a strong fleet fuel management system. Since refrigeration systems run separately from the truck engine, reefer fuel requires its own tracking, oversight, and cost controls.
One best practice is to track your fuel consumption by hour. Once you know your average reefer fuel consumption rate, monitoring runtime hours alongside fuel levels helps you catch abnormal usage or potential mechanical issues early.
It is also important to schedule preventive maintenance. Keeping trucks well-maintained will go a long way toward improving overall efficiently, and a proactive maintenance schedule helps prevent unexpected breakdowns and costly disruptions.
Using telematics for real time monitoring can further strengthen oversight. Modem fuel monitoring systems allow you to track reefer runtime, fuel levels, and temperature logs remotely, giving dispatchers better visibility and the ability to quickly address potential problems.
Finally, be sure to build reefer costs into load pricing. While reefer fuel is typically included in standard rate negotiations, it is important to account for increased fuel consumption during extreme temperatures and extended dock waits so margins remain protected.
In-Summary: What Is Reefer Fuel?
Reefer fuel is red-dyed, off-road diesel that’s used to power refrigeration units on temperature-controlled trailers. It has slight chemical differences from standard diesel fuel, and because it’s only intended for non-highway use, it isn’t subject to the same highway taxes.
If you’re hauling anything that needs to stay cool, reefer fuel is essential, but you have to be careful how you use it. Understanding usage rates, compliance rules, and cost considerations can help your fleet avoid legal penalties and protect your bottom line.
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Reefer Fuel FAQs
Can reefer fuel be used in a truck engine?
No, reefer fuel can’t be used in a truck engine for two reasons. First, reefer fuel is illegal to use in your engine because it’s not subject to highway taxes and it’s intended for powering refrigeration systems, not semi-trucks. Second, because reefer fuel isn’t designed for high-compression engines, it can cause damage to your system.
Why is reefer fuel dyed red?
Reefer fuel is dyed red to indicate that it’s untaxed for highway use, allowing regulators to easily detect misuse. Compared to clear diesel fuel, the red-dyed fuel leaves marks in your fuel tank and shows up with a blacklight.
Is reefer fuel the same as red-dyed diesel?
Yes, the terms “reefer fuel” and “red-dyed diesel” are often used interchangeably.
How much reefer fuel does a refrigerated trailer use per day?
Most reefer trailers use between 10 and 35 gallons per day, depending on temperature settings and conditions.
Where can I legally buy reefer fuel?
You can buy reefer fuel at truck stops, bulk fuel suppliers, and locations that sell off-road or dyed diesel.
What happens if you use reefer fuel illegally?
Using reefer fuel in your engine can cause serious damage to your fuel system components. If you’re caught by the DOT, you’ll face compliance violations and be charged federal fines of $1,000 or $10 per gallon, whichever is more.
Michael McCareins is the Content Marketing Associate at altLINE, where he is dedicated to creating and managing optimal content for readers. Following a brief career in media relations, Michael has discovered a passion for content marketing through developing unique, informative content to help audiences better understand ideas and topics such as invoice factoring and A/R financing.
