Reefer fuel is the diesel that powers the transport refrigeration unit (TRU) on a refrigerated trailer, held in a tank separate from the tractor. It is ordinary diesel, but it is tracked as its own category because it is consumed per hour of runtime rather than per mile, and because refrigerated trailers that transport perishable goods such as food and pharmaceuticals cannot survive a fuel-out. At truck-stop reefer islands it is often sold red-dyed and untaxed for road use; on over-the-road trailers in Florida, Exigo Fuels delivers on-road ULSD to TRU tanks.

What is the difference between tractor fuel and reefer fuel?

Both are diesel fuels, but they live in different tanks and are consumed on different clocks. Tractor fuel powers the truck engine and is budgeted per mile; reefer fuel powers refrigerated trailers and is budgeted per hour of TRU runtime — roughly 0.7 to 1.0 gallon per hour in South Florida summer heat. A tractor filled to the top can still be pulling a TRU with three hours of fuel left, which is why the two types of fuels need separate fill plans.

What fuel do reefer trailer TRUs use?

Transport refrigeration units run on ultra-low sulfur diesel (≤15 ppm sulfur), the same grade as the tractor. Dyed off-road diesel is legally permitted in a TRU fed from its own dedicated tank, because the reefer engine does not propel the vehicle — that is the fuel truck stops sell at a reefer island. What is not permitted is a shared tank: dyed fuel in a tank that also feeds the tractor is a federal violation starting at $1,000 or $10 per gallon under IRS §6715. Exigo Fuels delivers clear on-road ULSD to TRU tanks by default so a single grade covers both tanks.

How much diesel does a reefer TRU use per hour in Florida?

In South Florida's hot and humid climate, TRU fuel consumption ranges from 0.5–0.7 gal/hr for mild-set-point loads in cooler weather to 0.85–1.0 gal/hr for frozen cargo in summer heat. Pre-cooling an empty trailer from ambient to 34°F can consume 1.5–2.0 gal/hr for 2–4 hours. Budget roughly 0.7–1.0 gal/hr per reefer trailer for South Florida summer planning purposes.

Is reefer trailer TRU fueling the same as truck fueling?

No — TRU tanks are separate from tractor fuel tanks and must be filled independently. The TRU fill point is on the trailer front, not the truck cab, requiring the driver to physically access a separate fill port. Many fleets discover too late that a tractor with a full tank can have a TRU with 3 hours of runtime remaining, leading to mid-route temperature excursions or cargo loss.

Reefer Trailer Fueling: Fleet Manager Guide

Reefer trailers have two separate and independent fuel systems: the tractor engine fuel tank, and the transport refrigeration unit (TRU) fuel tank. The TRU — the diesel-powered unit that maintains cargo temperature — runs continuously whether the truck is moving or parked. For South Florida cold chain operations, TRU fuel management is as important as truck fuel management, and it requires a different approach.

What is reefer fuel?

Reefer fuel is the diesel that powers the refrigeration unit on a refrigerated trailer, drawn from a tank that is separate from the tractor's own fuel tank. It is not a different product from a chemistry standpoint — it is ordinary diesel — but the industry treats it as its own line item because it is metered, budgeted, and filled separately from the fuel that moves the truck.

Three things define it:

What it powers: reefer fuel powers the TRU, a small self-contained diesel engine and compressor mounted on the nose of the trailer. It is the fuel that keeps power refrigerated trailers cold. It runs whether the truck is rolling, backed into a dock, or parked overnight, which is why refrigerated trailers consume fuel on hours, not on miles.
Tractor fuel vs reefer fuel: the two never share a tank on a modern over-the-road reefer. Tractor fuel is measured in gallons of fuel per mile; reefer fuel is measured in gallons of fuel per hour of runtime. A fleet that budgets only the first is under-budgeting its real fuel usage and its operational costs by 15–25% on refrigerated lanes.
Why it exists as a category: because the load is temperature-critical. Trailers that transport perishable goods such as foods, pharmaceuticals, produce, and dairy cannot afford a fuel-out — the cargo is lost long before the trailer is.

You will also see reefer fuel sold red-dyed at dedicated truck-stop reefer islands, priced without highway road taxes. That is where the "red dye" association comes from, and it is the single most confused point in reefer fueling. For over-the-road trailers running in Florida, Exigo Fuels delivers on-road ULSD to TRU tanks — see the compliance section below for what type of diesel fuel is legal in a TRU and why red dyed diesel is the wrong call on a highway trailer.

How TRU (transport refrigeration unit) fueling works

Every refrigerated trailer has a self-contained diesel generator — the TRU — mounted at the front of the trailer. The TRU has its own fuel tank (typically 15–25 gallons) and runs independently of the tractor. It consumes diesel at a rate of approximately 0.4 to 1.0 gallon per hour depending on ambient temperature, set point temperature, and cargo load.

In South Florida, where ambient temperatures regularly exceed 90°F, TRU fuel consumption is at the high end: a trailer set to 34°F (produce) or 0°F (frozen) in Miami summer heat will burn 0.7–1.0 gallon per hour. A 24-hour layover at a distribution center in Miami could consume 17–24 gallons just for refrigeration.

The TRU tank is filled separately from the tractor — it is physically on the trailer, not the truck. This creates a logistics gap that catches fleet managers off guard: a truck driver who fills up the tractor and forgets the trailer might leave the DC with a tractor full of fuel and a TRU tank with 3 hours of runtime left.

TRU fueling options in Florida

There are three practical ways to keep reefer TRUs fueled in South Florida:

Driver self-service at retail diesel stations: The driver fills the TRU tank from the same retail pump as the tractor (TRUs use on-road ULSD). Simple but expensive (retail price) and time-consuming — the TRU fill point is on the trailer front, which requires repositioning from the truck cab. Many drivers skip it when the tank reads above half.
DC fueling island with TRU fill points: Large distribution centers in South Florida (Sysco, US Foods, major grocery DCs) have dedicated TRU fueling lanes. If your DC has this infrastructure, mandate that drivers fill TRU tanks on every departure as part of the departure checklist.
Mobile on-site reefer fueling: A fuel truck visits your yard or DC and tops off TRU tanks on all parked trailers while drivers are in the building. No driver time, no repositioning, and the fuel truck visits on a schedule tied to your fleet's layover patterns. This is the model Exigo Fuels provides for refrigerated fleet operators in the tri-county area.

TRU fuel consumption estimates for South Florida

Planning your reefer fuel budget requires realistic consumption estimates. Key variables:

Operating condition	Typical TRU fuel consumption
Fresh produce (34–40°F set point), Miami summer	0.7–0.9 gal/hr
Frozen cargo (0°F set point), Miami summer	0.85–1.0 gal/hr
Dairy/deli (34°F set point), mild weather	0.5–0.7 gal/hr
Pre-cooling an empty trailer (90°F→34°F)	1.5–2.0 gal/hr for 2–4 hrs
Full load, door open frequently (delivery route)	0.9–1.2 gal/hr

A 15-trailer reefer fleet doing 10-hour delivery days in Miami-Dade will burn approximately 700–1,000 gallons per day just in TRU fuel — separate from tractor fuel. Failing to account for this in the fuel budget is a common and expensive mistake.

Florida compliance for reefer operations

TRUs are not exempt from EPA emissions regulations. Florida follows federal Tier 4 TRU engine requirements for new units. Key compliance points:

15 ppm sulfur diesel, from a dedicated TRU tank: TRUs need ≤15 ppm sulfur diesel to protect their Tier 4 aftertreatment. On the tax side, a TRU fed from its own separate tank is a non-propulsion use, so dyed off-road diesel is permitted under IRS §4082 and Florida F.S. §206.874 — that is why truck stops sell dyed reefer fuel at their own island, priced without road taxes. The violation is a shared fuel system: if the TRU draws from the tractor tank, dyed fuel in that tank is the same federal offense as dyed fuel in the truck cab, starting at $1,000 per violation or $10 per gallon under IRS §6715. Exigo Fuels delivers clear on-road ULSD to TRU tanks by default, so one grade covers both tanks and a roadside dye test is never a question. See our red diesel cost and fines guide for the full enforcement picture.
California ARB TRU regulations: If your trailers ever enter California, they must comply with CARB's TRU ATCM requirements. This is not a Florida regulation but affects any fleet with a national route network.
Temperature logging for food safety: Florida DACS and FDA Food Safety Modernization Act rules require temperature logs for food transport. Make sure your TRU fuel plan prevents any fuel-out that could cause a temperature excursion — a cargo loss from a fuel-out is a FSMA documentation problem as well as a financial one.

Mobile reefer fueling for South Florida fleets

For refrigerated fleet operators in Miami-Dade, Broward, and Palm Beach who want to eliminate TRU fuel management from their drivers' responsibilities, Exigo Fuels provides scheduled on-site TRU fueling service. A fuel truck visits your yard on a fixed schedule, tops off all TRU tanks, records per-unit volume, and provides a consolidated invoice. Drivers depart with full TRUs. No retail station runs, no missed fills, no fuel-out cargo losses.

To set up a mobile reefer fueling program for your cold chain fleet, call (305) 900-6725 or request a fleet fuel consultation online.