Diesel fuel is categorized into different types, each suited for specific uses and conditions. Whether you're fueling a diesel pickup, farm equipment, or off-road machinery, understanding the types of diesel fuel - especially #1, #2, and #4 - can help you make the right choice for performance, climate, and longevity. In this guide, we break down the types of diesel fuel and when to use each.
Types of Diesel Fuel: #1, #2, and #4 Explained
Diesel fuels are broken up into 3 different classes: 1D(#1), 2D(#2) and 4D(#4). The difference between these classes depends on viscosity (the property of a fluid that causes a resistance to the fluid’s flow) and pour point (the temperature at which a fluid will flow).
#4 Diesel Fuel: For Low-Speed Equipment
#4 fuels tend to be used in low-speed engines.
#2 Diesel Fuel: The Most Common Type
#2 fuels are used in warmer weather and are sometimes mixed with #1 fuel to create a competent winter fuel.
#1 Diesel Fuel: Benefits and Cold Weather Use
#1 fuel is preferred for cold weather as it has a lower viscosity. It used to be standard to see the fuel # on the pump, but a lot of gas stations do not state the fuel number anymore.
Diesel Grades and Cetane Rating
Another important factor is the rating of Cetane in the diesel fuel. Cetane is similar to Octane for gasoline fuel and it indicates how easy the fuel will ignite and burn. Since Ultra low Sulfur diesel fuels became standard in the middle 2000s, the cetane has been reduced which makes the newer fuel less desirable for diesel enthusiasts. It is highly recommended to run a fuel additive to increase the overall Cetane number. Diesel fuel additives such as Fuel Bomb will also have lubricity additives which will help the modern diesel engine run better and achieve a higher fuel economy(MPG). One other feature of a diesel fuel additive is that it does not need much per tank. A standard bottle of diesel fuel additive usually treats 250-500 gallons.
Here is an article from Diesel Power Magazine on diesel fuel additives and why they are important.
Synthetic diesel comes from several sources such as wood, straw, corn and even garbage or discarded foods.
Biodiesel is an ecologically-friendly type of diesel. It is a cleaner-burning diesel made from natural, renewable sources such as vegetable oils and animal fats. Biodiesel is helping to reduce American dependence on foreign petroleum. It is also helping in the creation of green jobs and the improvement of our environment.
Frequently Asked Questions:
What are the three types of diesel fuel?
The three main types are #1, #2, and #4 diesel. Each differs in viscosity and performance, making them suited for specific applications and climates.
What is the difference between #1 and #2 diesel fuel?
#1 diesel is thinner and flows better in cold weather. #2 diesel has more energy content and is more commonly used in standard on-road vehicles.
Can you mix #1 and #2 diesel fuel?
Yes. In colder climates, they are often blended to improve cold-weather reliability without sacrificing performance. However, for on-road use vehicles, you must specifically use #2 fuel as #1 is not rated for highway use.
Are all diesel fuels the same?
No. Diesel fuel types differ in their composition, cetane levels, and additives. Some are better suited for cold climates or heavy-duty use.
What type of diesel fuel should I use in my truck?
Most trucks run on #2 diesel, but in very cold temperatures, a winterized diesel blend is recommended to prevent gelling.
What is #4 diesel used for?
#4 diesel is thicker and intended for low-speed, off-road industrial equipment like generators or construction vehicles. It’s not meant for most consumer vehicles.