The Different Types of Diesel Fuel: #1,#2, and #4

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 fuels tend to be used in low-speed engines. #2 fuels are used in warmer weather and are sometimes mixed with #1  fuel to create a competent winter fuel.  #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.

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.

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  1. Pingback: diesel fuel - OIL WORLD 2011 – OIL WORLD 2011
    1. I would assume that sign is designed for traffic patterns instead of an actual different type of diesel. There often are pumps that can handle larger vehicles and trucks and so they want those people to use the truck pumps. There should not be a difference between the 2 fuels. There is a possibility that specific fuel stations add in fuel additives that truckers would like. I honestly do not know why they would mention a difference.

    2. One difference I’ve found at fuel stations between “truck diesel” and “car diesel” is the nozzle for the “truck diesel” is too large to correctly fit in my VW Jetta.

      Here is another diesel fuel difference. You can get “off-road” diesel, but that is for farm tractor use, or perhaps grading equipment. It does not have the highway tax added to it. It is dyed red so if you are caught with it in your car or truck driving down the road you will be in trouble.

  2. When purchasing fuel I was offered Biodiesel or regular. I responded that I would take “what ever”. I have noticed a lot of rust occurring on fuel caps and main tanks. Is this due to the type of fuel? I am aware of ethanol absorbing moisture in marine applications, could there be an issue here?

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