If your fleet hauls temperature-sensitive cargo, using reefer fuel is critical for maintaining product integrity and operational efficiency. But what is reefer fuel exactly? How does it differ from tractor fuel? And what cost savings does it offer?
This guide will explain reefer diesel—also referred to as off road or red dyed diesel—including how it works, how much cheaper it is than tractor diesel, where to purchase it, and how to file for a reefer fuel tax refund. We’ll also explain how truck stops handle reefer fueling, whether it’s safe for your truck, and how to purchase it. Whether you’re an owner-operator or oversee a fleet of refrigerated units, understanding reefer fuel can help you control fuel expenses, navigate regulations, and ensure your shipments remain at the ideal temperature.
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Reefer fuel is a type of diesel fuel also known as off road diesel or red dyed diesel which is used to power refrigerated truck trailers, commonly called reefers, that keep perishable goods such as food and medicine at the proper temperature during transport. Unlike the diesel fuel that powers a truck’s engine, reefer fuel is exempt from federal and state road taxes since it is used only for the refrigeration unit that cools the trailer.
Reefer fuel and tractor fuel are both diesel and have the same chemical composition. Reefer diesel is dyed red to make it easy to spot and prevent illegal use in tractor fuel tanks. During traffic stops, DOT checkpoints, and inspections at state line weigh stations, authorities often check fuel tanks for this red dye. Because of its distinctive color, reefer diesel is commonly called red diesel, red dyed diesel, or off road diesel.
Reefer trailers burn 0.4 to 3 gallons per hour, depending on the following factors:
Refrigerated trailer fuel tank capacities usually range from 40 to 100 gallons.
Use the reefer trailer calculator below to calculate hours to empty tank after refilling, refills per week, and total fuel used per week.
Reefer diesel typically costs 32 to 90 cents less per gallon than regular tractor diesel, depending on the state. The price difference comes from tax exemptions since reefer diesel is not subject to the federal excise tax (FET) of 24.4 cents per gallon or the state excise tax (SET) that applies to regular diesel fuel. State taxes vary widely: Alaska has the lowest diesel SET at 8 cents per gallon, while California has the highest at 46.6 cents per gallon.
Some states, like California, also apply a different sales tax rate for reefer diesel, creating even more savings for reefer trucking companies.
Since reefer fuel is diesel and has the same chemical composition as tractor diesel fuel, it will not hurt your truck if you were to accidently put it in your tractor tank. However, it is illegal to use reefer fuel in your tractor tank, and if you are caught with red dyed diesel in your tank, you can be heavily fined.
Many truck stops have the option to select reefer fuel at the normal diesel pumps after you swipe your fuel card. If you select this option, you will first fill the tractor tanks, hang up the nozzle, and then the pump will automatically start a new transaction, allowing the driver to begin fueling the reefer tank with the same nozzle. The pump will dispense regular diesel, but it will separate the transaction on the receipt by diesel used in the tractor and diesel used in the reefer tank which makes it easier for trucking companies to file fuel tax exemption reports.
Since regular diesel is being dispensed, it is not exempt from road taxes at the time of purchase unlike red dyed reefer diesel that provides the tax exemption upfront. In this case, you'll have to file a fuel tax exemption form to receive a credit back for the fuel taxes you paid at the point of sale.
Search below for over 800 fuel stations that carry tax exempt reefer fuel (off road diesel) in the U.S. You can also see the map below and check out this list of fuel stations that carry reefer diesel.
Map of U.S. Fuel Stations that Carry Reefer Diesel
Because reefer fuel is primarily used by companies, you won’t usually find it at regular retail gas stations since the general public simply doesn’t need it. Instead, it’s sold at commercial fuel stations, also known as cardlocks. These stations cater to businesses like construction companies and trucking fleets that regularly need red dyed diesel for machinery, generators, and refrigerated trailers.
In some states, you must have a permit to purchase red dyed diesel. For that reason, most commercial stations only sell it to customers with a fleet fuel card. Fuel card providers typically verify permits and paperwork before issuing accounts, which protects stations from the risk of selling dyed diesel to non-permitted buyers. If stations accepted cash or credit cards, they’d have no way to verify this information, potentially creating legal liability.
The largest network of commercial stations carrying reefer diesel in the U.S. is the Commercial Fueling Network (CFN). If you want access to reefer diesel at CFN locations, you’ll need to sign up for a CFN fuel card.
You can use regular diesel at any gas station or truck stop to fill your reefer tank and claim a fuel tax credit later since you paid fuel taxes at the time of purchase and used the fuel in a reefer tank, which is exempt from road taxes. This method is more costly upfront because you have to pay road taxes, unlike when purchasing red-dyed reefer diesel, which is tax-exempt at the time of purchase.
You just need a way to identify fuel purchases made for the reefer unit. There are two ways you can do this.
If you fill up at truck stops that have the reefer fuel option at the pumps, you can use a fuel card or credit card to purchase fuel and keep the receipt with the separate line item for reefer diesel to file your fuel tax refund.
Fleet fuel cards prompt for odometer before every fuel purchase. For tractor purchases, the driver can enter the truck odometer and for reefer fuel purchases, the driver can enter a designated number you give them to identify reefer fuel purchases in your fuel card reporting. For example drivers can enter "1" at the pump and in the odometer column in your reporting you'll see "1" for all the reefer fuel transactions.
If you purchase regular diesel for your reefer trailers, you'll want to file for a tax refund with the federal government and the states where you purchased fuel in. Keep in mind you don't need to file for a refund if you purchase red dyed reefer diesel at the pump because you did not pay fuel taxes at the time of purchase. Here are the steps to file a reefer fuel tax refund:
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