Why does diesel change color when stored for a long time?

The darkening of light diesel oil during storage is caused by the elemental composition of petroleum, and the hydrocarbons in it are most affected.

It is broadly divided into alkanes.

Naphthenes, aromatic hydrocarbons.

and unsaturated hydrocarbons, etc. The chemical stability of hydrocarbon components is poor, and long-term contact with air makes it easy to oxidize to form gum, so the longer the diesel is stored, the darker the color.

Diesel has no expiration date.

However, the longer the time, the combustion rate will gradually decrease, and the diesel will become darker after being in the tank for a long time, the residual carbon of the distillation residue will increase, and the gum content will increase. If the requirements are strict, it is best to seal with nitrogen for storage.

The color of diesel depends on the stability of the diesel. The stability of diesel fuel is the ability of diesel fuel to resist oxidation during storage and use. Diesel with good stability does not change much in appearance and color during storage, and it is not easy to produce gum.

After a certain period of storage of diesel fuel with poor stability, the color will become significantly darker, and the gum will increase, which will affect the normal use. In addition to the influence of storage conditions, the stability of light diesel oil is mainly determined by its chemical composition. Diesel oil blended with two processed fractions contains more olefins, has poor stability, is easy to oxidize, and is not suitable for long-term storage.

The base oil added to diesel has the same weathering effect as oxidation, and the longer the storage time, the lower the combustion point of some of them.

Because the additives in the middle are different, 0 diesel and -10, -20 diesel colors are not the same.

In the refining, the oil product is composed of a mixture of hydrocarbons, mainly containing 918 carboproalkanes, naphthenes or aromatic hydrocarbons, and its physical properties are located between gasoline and heavy oil, with a boiling point between 170 and 390 and a specific gravity.

At 20°C, the shelf life of diesel fuel is at least 12 months, and there are many unstable substances and volatile components in the oil, which is easy to deteriorate. For example, the color of FCC diesel does not go through hydrotreating, and it changes color in two days.

From the perspective of inspection and sample retention, the general diesel sample retention time is 3 months, indicating that the diesel fuel can ensure product quality (in line with the national standard) at least 3 months.

Diesel is at least 12 months or even about a few years, and there is also a saying that diesel has no shelf life, but it will burn insufficient after a long time.

From a practical point of view, refined oil generally enters the market directly and will not be stored for 3 months or more. If it comes into contact with metals such as water, copper, and zinc during storage, it will accelerate decomposition.

What are the factors that affect the shelf life of gasoline and diesel?

Reduced octane number, volatilization of combustion substances, oxidation status, etc., are all factors that directly affect the shelf life of gasoline.

Diesel fuel is stored for a long time, and the combustion rate will slowly decrease. In diesel refining, the oil product is composed of a mixture of hydrocarbons, mainly containing 918 carboproalkanes, naphthenes or aromatic hydrocarbons, and the physical properties are located between gasoline heavy oil, with a boiling point between 170 and 390 and a specific gravity.

What are the consequences of using expired gasoline and diesel?

The direct manifestation of expired gasoline and diesel is the lack of power, which will then cause rough operation of the engine, and over time, it will cause blockage, carbon deposition and other problems, which will have a direct impact on the engine.

At present, China's oil consumption is large, and refined oil generally enters the market directly, and it is generally not stored for more than 3 months in the sales process.

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Can diesel still be used if it has been stored for a long time and its color has become darker?

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After a long time, the color has changed slightly, and this can still be used. Because there is this chemical additive in this diesel, it has been a chemical additive for a long time. After a long time, there will be discoloration, but this quality of this diesel oil.

That is to say, there is no impact on the performance of this diesel, or it can be used continuously, this has nothing to do with it, it can be added directly to the car for normal use.

Summary. Hello, diesel fuel is stored for a long time, this is not recommended. First, depending on the storage time, if it is not more than a year, there is no problem with this.

Second, long-term storage of diesel, even if it is stored in a good environment, the unsaturated hydrocarbons contained in diesel fuel are easy to oxidize and gelatinize, destroying the stability of diesel. Third, diesel has a stability index, that is, the actual gum index. In fact, diesel with large gelatinous content is easy to generate carbon deposits and colloidal sediment in the combustion chamber, which will cause the deterioration of engine work and serious premature damage to the engine.

So the recommendation is not to use.

Hello, diesel fuel is stored for a long time, this is not recommended. First, depending on the storage time, if it is not more than a year, there is no problem with this. Second, long-term storage of diesel, even if it is stored in a good environment, the unsaturated hydrocarbons contained in diesel fuel are easy to oxidize and gelatinize, destroying the stability of diesel.

Third, diesel has a stability index, that is, the actual gum index. In fact, diesel with large gelatinous content is easy to generate carbon deposits and colloidal sediment in the combustion chamber, which will cause the deterioration of engine work and serious premature damage to the engine. So the recommendation is not to use.

Six or seven years.

Hello, stored for 6 to 7 years, this is not available for normal use.

The color of diesel fuel darkens over time and is due to the elemental composition of petroleum.

Among them, the hydrocarbons that have the greatest impact are roughly divided into alkanes, naphthenes, aromatic hydrocarbons and unsaturated hydrocarbons. However, the chemical stability of hydrocarbon components is poor, and long-term contact with air makes it easy to oxidize to form colloids, so the longer the diesel is stored, the darker the color.

Precautions for the storage and use of diesel:

1. Prevent water and mechanical impurities from being mixed.

2. It is strictly forbidden to mix with gasoline for lighting or as fuel for kerosene furnaces.

3. Diesel must be precipitated, filtered, and impurities and water removed before use to ensure the normal operation of the diesel engine fuel supply system.

4. At low temperature, in order to improve the low-temperature fluidity of diesel, a small amount of kerosene is allowed to penetrate into the diesel, but the flash point may be unqualified. However, it is never allowed to add gasoline to diesel to improve the low-temperature fluidity of diesel.

5. Diesel oil of the same grade and different grades, because their quality indicators are basically the same except for the freezing point and cold filter point, so when the resources are insufficient, they can be mixed with oil at a suitable temperature.

6. Strictly prevent exposure to the sun and open flame heating, and store at a lower temperature as much as possible. In winter, the necessary preheating can be carried out when diesel is used.

It's best not to use it, diesel storage requires sealing and protection from light, like yours have turned black, indicating that the diesel rubber has become heavier, there is no problem with use, but it will cause damage to the engine. It is not recommended to use it as an engine oil, but it can be considered for diesel stoves.