In our everyday lives, we rely on fuel more than we often realize. While all fuels might seem similar at first glance, understanding their differences is important, especially when it comes to safety, efficiency, and the environment.
Jet fuel helps aircraft travel long distances quickly and safely, while diesel powers many of the vehicles and machines we depend on daily. It doesn’t come as a surprise that airborne vehicles need something separate in composition from diesel or gasoline to function efficiently. So, what’s the difference between jet fuel and diesel?
Let’s have a look at jet fuel vs diesel and get to know these fuels a bit better.
What Is Jet Fuel?
Jet fuel is a kerosene-based fuel made specifically for gas turbine engines in aircraft. The most common types of aviation fuels are:
- Jet A — used mainly in the US for commercial aviation, with no anti-static additives unless specifically required
- Jet A-1— an international aviation fuel, also used by the US military, antistatic additives are added as a default
- JP-8 — enhanced version of Jet A1 with corrosion inhibitors and lubricity improvers, used primarily by NATO forces as well as the US military.
Aviation fuels undergo extensive refinement processes and include special additives, which might explain their high costs. These include anti-icing agents that help prevent fuel from freezing at high altitudes while antioxidants improve fuel stability and extend shelf life.
One of the major characteristics of jet fuel is the high energy density, which provides the power to aircraft for takeoff and long-distance flights. Compared to diesel, the fuel has excellent cold-weather performance due to additives as well as its own individual properties that allow it to stay fluid at high altitudes where the temperature drops below freezing point.
What is Diesel?
Diesel is a petroleum-based fuel used in internal combustion engines. Its composition typically includes paraffins that contribute to energy content and combustion properties; aromatics to help with ignition characteristics; and cycloalkanes to add to fuel stability and performance under load.
It is heavier and less refined than gasoline, and gives more energy, allowing it to produce high torque at lower RPMs, making the fuel perfect for the high-demand environments diesel-powered vehicles work in.
The engines are durable and the fuel provides better mileage, especially in heavy-duty applications, like commercial vehicles, heavy machinery, generators as well as freight trains, allowing it to be used widely across various ground-based and industrial settings.
Jet Fuel Vs. Diesel
Although both jet fuel and diesel are an important part of the transportation industry, there are several differences between the two fuels that you should be aware of.
Composition
Jet fuel is a highly refined, kerosene-based fuel with additives that enhance stability. Its light, molecular structure allows it to remain fluid in extreme cold and burn cleanly in turbine engines.
Diesel is produced during the distillation process of crude oil, making the foundation of the fuel entirely different. It is less refined than jet fuel and contains a mix of paraffins, aromatics, and cycloalkanes, which makes it denser and more oily than jet fuel.
Performance
Diesel contains 45.5 MJ/kg, slightly higher than jet fuel’s 43 MJ/kg, which makes the latter optimized for a high power-to-weight ratio, as it burns efficiently in turbine engines, offering consistent thrust and stable combustion across a wide range of conditions.
Compression ignition engines are built to handle the stress of constant load and pressure. Diesel offers greater torque and energy per liter, making it better for ground-based power and endurance, even though it may be slightly less efficient than jet fuel.
Applications
Jet fuel is used in commercial airliners, military jets, cargo planes, helicopters, turboprop aircraft, as well as some drones and experimental aircraft; all airborne vehicles. It’s not suitable for ground vehicles as it lacks most of the properties of land-based fuels, like lubrication and the energy required to start up engines, leading to malfunction.
Diesel is much more versatile, being used in most spheres of the industry. Construction and agricultural machinery, trains (especially freight locomotives), backup power generators, ships and marine engines, and even some passenger cars and SUVs, all enjoy the power offered by diesel engines and the fuel.
Environmental Impact
Since jets operate at high altitudes, emissions from aircraft have indirect effects on climate change. Contrails and contrail-induced cirrus clouds trap heat, increasing the temperature in the upper atmosphere. Aviation is responsible for around 2-3% of global CO₂ emissions, along with nitrogen oxides and particulate matter.
Diesel engines emit higher levels of nitrogen oxides and sulfur content than turbine engines. The fuel also forms a major source of fine particulate pollution, which can cause respiratory and cardiovascular issues. Although efforts have been made to lessen the damage caused by diesel engines, with the introduction of ULSD and diesel particulate filters, the environmental impact remains significant in urban areas.
Pricing and Availability
Jet fuel prices are slightly higher than diesel, due to the fuel’s complex refining process, but also fluctuate with market conditions and seasonal demand for air travel. Jet fuel is widely available at airports around the world, especially at commercial airports where airlines and military aviation are the primary customers.
Diesel is also impacted by global oil prices, but the rate is more stable. It is easily accessible in urban, rural, and remote locations for ground vehicles and machinery.
Can Diesel be Used as Jet Fuel?
Diesel’s slower burn rate makes it incompatible with the fast, efficient combustion required by jet engines. Due to its aerated quality, jet fuel is optimized for jet engines, where it is atomized and burns in a controlled, continuous way.
Diesel engines use the combustion ignition process, which works well for ground vehicles and heavy-duty machinery, but becomes too slow and heavy for flights, where weight and responsiveness matter
In terms of fuel system compatibility, diesel’s higher viscosity and slower flow characteristics would clog fuel systems in aircraft, and its combustion process is unsuitable for the high-speed and high-altitude demands of jet engines.
Other than that, using diesel as a jet fuel is a safety hazard. It could cause incomplete combustion, resulting in carbon buildup, increased engine wear, and potentially catastrophic failure due to overheating, instability, or loss of power.
Can You Use Jet Fuel In A Diesel Engine?
When jet fuel is used in a diesel engine, its lower lubricity can lead to increased wear and tear on crucial components like fuel injectors and fuel pumps. Injector damage is particularly concerning because injectors are critical for the precise spraying of fuel into the combustion chamber, and any degradation in their function can affect overall engine performance.
If jet fuel is used in a diesel engine, it often requires the addition of specialized lubricity additives and cetane improvers to help with ignition, since jet fuel has a lower cetane rating than diesel. Without these additives, the engine may experience rough idling, difficulty starting, and poor performance due to incomplete combustion and excessive wear.
In some emergencies, when diesel fuel is unavailable but jet fuel is available, an engine might temporarily run on jet fuel. For instance, if a diesel-powered vehicle is stranded or in an area where only jet fuel is accessible (such as an airport or military base), it can use jet fuel as a short-term solution to keep the engine running until proper diesel fuel is obtained.
Military vehicles and machines that are designed to operate on both jet fuel and diesel can switch to jet fuel without causing major issues in the short term. However, as with any non-ideal fuel, prolonged use of jet fuel in diesel engines can lead to increased wear, reduced efficiency, and potential maintenance issues.
The Importance of Using the Right Fuel
Jet fuel and diesel are both essential fuels in their respective industries. However, there are stark differences between the two fuels, making them excellent for their intended purposes, but potentially disastrous when replaced with one another. Jet fuel is designed specifically for turbine engines in aviation, with qualities like clean-burning combustion and excellent cold-weather performance to ensure safe, efficient flight. On the other hand, diesel is formulated for internal combustion engines, offering high torque and fuel efficiency in ground-based applications like vehicles and machinery.
Understanding the difference between jet fuel and diesel is important to keep engines running smoothly, safely, and efficiently. Whether you’re on the runway or the road, the right fuel makes all the difference.
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FAQs
1. Is jet fuel just kerosene?
Jet fuel, specifically Jet A and Jet A-1, is primarily kerosene-based, but it also contains specialized additives like anti-icing agents and antioxidants to help it perform reliably at high altitudes and cold temperatures.
2. How much is jet fuel per gallon?
Prices can vary depending on location, market conditions, and whether it’s for commercial or military use. As of early 2025, jet fuel typically ranges from $4 to $6 per gallon in the US, but it can spike higher during periods of global fuel volatility. It’s usually priced in bulk for airlines, so retail prices aren’t often listed like gasoline or diesel.
3. What happens if you put jet fuel in a gasoline engine?
Gasoline engines are not designed to handle the combustion properties or viscosity of jet fuel. If you fill a gasoline engine with jet fuel, it could lead to poor ignition, misfires, or even engine damage. At best, the engine runs rough. At worst, it might not run at all.
4. What octane is jet fuel?
Jet fuel doesn’t use the same rating system because it’s designed for turbine engines, not spark-ignition engines like those that use gasoline. If we tried to measure it that way, its effective octane would be very low, around 15 to 25, which is far too low for gasoline engines.
5. Is jet fuel more expensive than diesel?
Jet fuel can sometimes be slightly more expensive, due to special refining processes and additives. Since both are derived from crude oil and affected by the same global supply factors, their prices often rise and fall together.
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