Diesel #1 vs #2: What Is The Difference Between Them?

Although diesel is considered one of the most efficient fuel sources, which type of diesel to choose is a riddle all drivers should figure out to ensure its efficiency. 

Diesel #1 and #2 do not share the same properties and perform very differently under cold and hot temperatures; therefore, putting the wrong one in the fuel tank will dampen your car’s operation and your driving experience in the long run. Let us explain how these two fuels work and clear all your confusion.

What Is The Difference Between Diesel #1 and #2?

Diesel #1 works great in colder temperatures and is less likely to get gelled, thanks to its higher cetane rating. Its lower cloud point than #2 also ensures the fuel remains liquid in all conditions. However, #2 has a higher energy content, making the engine more efficient at warmer temperatures. It is also cheaper and more accessible than #1, available in almost every gas station.

diesel 2
Diesel #2

1. Viscosity

Diesel #1 has a much lower viscosity, meaning its thickness is reduced to ensure easier and better flow through the engine components and fuel systems, even in colder conditions. As a result, it is a favorite among drivers living or traveling through regions with a harsh winter, reducing the risk of performance issues and fuel gelling.

On the other hand, diesel #2 is thicker and less fluid. This helps prevent fuel leakage in warmer climates but might lead to filter clogging, an increased gelling risk, and a slower fuel flow when the temperature drops.

2. Energy Content

The lower energy content in Diesel #1 does not impact the engine’s ability to generate power. Unfortunately, it often reduces the car’s fuel economy, so you must refuel the tank more frequently.

diesel #1
diesel #1

Meanwhile, #2 Diesel contains more energy per volume and offers much better mileage. As it allows vehicles to travel longer distances than #1 Diesel, this fuel is always the preferred choice for long-haul transportation. 

3. Cloud Point

The Diesel #1 has a lower cloud point and still stays liquid at lower temperatures, thanks to the removal of paraffin from its chemical mix. Therefore, no wax crystals can form in the fuel, ensuring the liquid is free-flowing even in extreme cold. 

On the contrary, #2’s higher cloud point makes it more vulnerable to wax crystallization. If you still want to use Diesel #2 in colder conditions, extra additives are needed to lower the cloud point and prevent gelling. 

4. Lubricating Properties

Diesel number two contains more aromatics and sulfur, both of which are excellent at reducing excessive friction between metal surfaces. 

Meanwhile, other lubricants, like polyalphaolefins (PAOs) and esters, are added to diesel #1 for better lubrication. There is no clear winner in this match.

5. Cost

Diesel #1 has a higher cetane rating and is much more difficult to produce; not to mention, some premium options also have to be extensively refined and blended with additives to improve cloud point and lubricity. As a result, it is more expensive than #2 and not always available in every shop and station.

On the contrary, no 2 Diesel is readily distributed in every gas station, commercial fueling station, and truck stop at a much cheaper price.

Which Is Better? When Should You Use Diesel #1 and #2?

Each option has its own advantage, so the decision boils down to your demands and budget. Diesel #2 is the superior choice if you are on a budget, as it offers excellent mileage and fuel economy while being cheaper. We suggest using Diesel #2 in warm (or mildly cool) weather.

Diesel #1, on the other hand, ensures a smooth flow and is less likely to gel in cold climates – a great fuel choice for snowstorms, rainfalls, and harsh winter months.

Can You Mix Number 1 and Number 2 Diesel?

Yes, there is no problem mixing them. Many fuel suppliers even blend #1 and #2 to create a winterized diesel fuel that generates great power while performing well in cold weather conditions.

However, before mixing, ensure they are clean and water-free. We also suggest using diesel fuel additives to make the most out of them. 

How Do #1 and #2 Differ From #4?

Both Diesel #1 and #2 are lighter than #4 and have higher cetane ratings. 

As the heaviest diesel option with the lowest cetane rating, #4 is mostly used as heating oil or in low-/medium-speed engines during industrial processes. It is also the most expensive. 


Diesel #1 is often used at cold temperatures, while diesel #2 works well for vehicles and equipment in hot or warm climates. You can blend the two to utilize their best properties, but ensure both are in good condition before mixing.

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Alex Lewis

Alex Lewis

Petroleum Engineer At Rex Energy

I have worked in a variety of roles and professions, from quality engineering in the automotive industry to production engineer in the oil and gas sector. From a technical point of view, these roles have shown me how to design a process, ensure it is efficient and up to standard, and manage the execution of the said process from start to finish.

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