The Difference Between Kerosene and Diesel Fuel. Both kerosene and diesel fuel are petroleum refinery products obtained through two methods—distillation or cracking. Despite this, they share only a common origin and a partial overlap in their use as fuel for different types of internal combustion engines. If we exclude their shared function as fuel, these two substances have very little in common. Their differences are due to their distinct chemical and physical properties. Let’s take a closer look at how kerosene differs from diesel fuel.
Historical Background
The term “diesel fuel” (often referred to as “solyarka” in Russian) comes from the German word Solaröl, meaning “solar oil.” In 1857, this term was used to describe a heavy fraction obtained during the distillation of crude oil. Later, it was adopted as fuel for low-speed diesel engines, which operate by igniting a mixture of diesel and air under very high pressure in the combustion chamber. Today, diesel engines are commonly used in:
- Agriculture (combines, tractors, etc.)
- Automotive transport (many buses, trucks, and some passenger cars)
- Rail transport (various types of diesel locomotives)
- Military equipment (tanks and other armored vehicles)
- Stationary power plants
Kerosene, on the other hand, has been used as lamp fuel since the mid-19th century. Unlike previous fuels used for lighting, kerosene burned completely, leaving no soot, keeping lamps clean, and producing no unpleasant odor. Because of its clean combustion, kerosene was later adopted as fuel for rockets and aviation. Apart from its use as engine fuel, kerosene has been utilized in many industries, including:
- Raw material for the chemical industry
- Firing of glass and porcelain products
- Household heating and lighting appliances (kerosene stoves, primus stoves, lamps, etc.)
- Solvent for industrial applications
- Traditional medicine (formerly used to treat lice and diphtheria)
- Pest control (historically used to wipe down furniture to kill bedbugs)
Comparison
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Kerosene is a mixture of hydrocarbons with a boiling point ranging from 150 to 250°C. It is a slightly oily, transparent liquid, with some types having a yellowish tint.
- Density at 20°C: 0.75–0.85 g/cm³
- Highly volatile, which contributes to its complete combustion.
- Storage requirements are strict, as kerosene vapors are explosive.
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Diesel fuel is generally heavier than kerosene, with a density of 0.84–0.86 g/cm³.
- Does not evaporate easily, making storage significantly simpler.
- Thickens at low temperatures, which is why summer and winter diesel fuel varieties exist.
- In cold temperatures, summer diesel fuel turns into a gel-like substance, making it difficult to start the engine.
- In the past, drivers had to heat the fuel tank externally (e.g., with a blowtorch), which was highly dangerous due to the risk of ignition.
- Today, winter diesel fuel is available, formulated with a lower density and lower freezing point to prevent thickening in cold conditions.
