Introduction of diesel lubricants

Diesel lubricants are specially designed lubricants for diesel engines. Not only does it play a key role in lubricating engine components and reducing friction and wear, it also plays an important role in cleaning, cooling and sealing the engine. Diesel engines usually work under high temperature and pressure conditions, requiring lubricating oil to have excellent thermal stability, oxidation resistance and high load bearing capacity. The choice and use of diesel oil is directly related to the performance and life of the engine.

1. Basic functions of diesel oil

1.1 Lubrication function

The most basic function of diesel oil is to lubricate the various moving parts inside the engine, such as pistons, cylinders, crankshafts and camshafts. By forming an oil film on the metal surface, diesel oil can effectively reduce friction between components, thereby reducing wear, reducing energy consumption and preventing engine overheating.

1.2 Cleaning function

Diesel oil has the function of cleaning the inside of the engine. The engine will produce carbon deposits, dirt and other impurities during the working process, which will affect the normal operation of the engine if not removed in time. Diesel oil contains a cleaning dispersant, which can effectively remove and disperse these impurities and keep the engine clean.

1.3 Cooling function

Diesel engine in the working process will produce a lot of heat, diesel oil through the internal circulation flow in the engine, take away excess heat, to help the engine heat, so as to prevent the engine overheating, to ensure that the engine in the appropriate temperature range.

1.4 Sealing function

Diesel oil can form a sealing oil film between the piston and the cylinder wall to prevent combustion gas leakage, thereby improving the combustion efficiency and power output of the engine. This oil film also prevents dust and impurities inside the engine from entering the combustion chamber and protects the engine components.

1.5 Corrosion protection

Diesel oil contains anti-corrosion agents to prevent the metal components inside the engine from being corroded by moisture and other impurities in the fuel, extending the service life of the engine.

2 Classification of diesel oil

2.1 Classification by Base oil

Diesel oil according to the base oil can be divided into mineral oil, synthetic oil and semi-synthetic oil three types.

2.1.1 Mineral oil

Mineral oil is a lubricating oil made from crude oil by distillation, refining and other processes. Its cost is lower, but the performance is relatively poor, suitable for diesel engines that are not harsh working conditions.

2.1.2 Synthetic oil

Synthetic oil is a lubricating oil made by chemical synthesis method, which has excellent high temperature stability, low temperature fluidity and oxidation resistance. The cost of synthetic oil is higher, but the performance is excellent, suitable for high performance diesel engines and extreme operating conditions.

2.1.3 Semi-synthetic oil

Semi-synthetic oil is a mixture of mineral oil and synthetic oil in a certain proportion, with the advantages of mineral oil and synthetic oil, performance and cost between the two, suitable for most diesel engines.

2.2 Classification by viscosity class

Diesel oil can be divided into single-grade oil and multi-grade oil according to viscosity grade.

2.2.1 Single grade oil

The viscosity of single-stage oil varies greatly at different temperatures, and it is suitable for working environments with little temperature change. Single-stage oils are classified into different viscosity grades according to SAE (American Society of Automotive Engineers) standards, such as SAE 30, SAE 40, etc.

2.2.2 Multigrade oil

Multistage oil has a stable viscosity at different temperatures and is suitable for working environments with large temperature changes. Multigrade oils are divided into different viscosity grades according to SAE standards, such as SAE 10W-30, SAE 15W-40, etc., where “W” indicates the low-temperature viscosity grade used in winter.

3. Composition of diesel oil

Diesel oil is composed of two parts: base oil and additive.

3.1 Base oil

Base oil is the main component of diesel oil, accounting for more than 80% of its total. The quality of base oil directly affects the performance of lubricating oil. There are three types of base oil: mineral base oil, synthetic base oil and biological base oil.

3.1.1 Mineral base oils

Mineral base oil is made from crude oil by distillation, refining and other processes, and has good lubricating properties and thermal stability, but poor oxidation resistance and low temperature fluidity.

3.1.2 Synthetic base oil

Synthetic base oils are made by chemical synthesis and have excellent high temperature stability, low temperature fluidity and oxidation resistance, providing excellent lubrication properties under extreme operating conditions.

3.1.3 Biobased oil

Bio-based oil is made from vegetable oil or animal fat after chemical modification, which has the characteristics of environmental protection and renewable, but its lubrication performance and stability need to be improved by additives.

3.2 Additives

Additives are an important part of diesel lubricating oil, usually accounting for 10%-20% of the total lubricating oil. The type and content of additives directly affect the performance of lubricating oil. Common additives are as follows:

3.2.1 Cleansing dispersant

The cleaning dispersant can remove and disperse carbon deposits and impurities inside the engine, keep the engine clean, and prevent the formation of deposits.

3.2.2 Antioxidants

Antioxidants can prevent the oxidation and deterioration of lubricating oil under high temperature conditions, extend the service life of lubricating oil, and keep the performance of lubricating oil stable.

3.2.3 Antiwear agent

Anti-wear agent can form a protective film on the metal surface, reduce friction and wear between metal components, and improve the durability of the engine.

3.2.4 Corrosion protection agent

Anti-corrosion agents can prevent the metal components inside the engine from being corroded by moisture and other impurities in the fuel, extending the service life of the engine.

3.2.5 Viscosity index improvers

The viscosity index improver can improve the viscosity stability of the lubricating oil at different temperatures, ensuring that the lubricating oil has sufficient viscosity at high temperatures and good flow at low temperatures.

4. Performance indicators of diesel oil

The performance indexes of diesel lubricating oil mainly include viscosity, flash point, pour point, total base value (TBN), sulfate ash content and oxidation resistance.

4.1 Viscosity

Viscosity is one of the most important performance indicators of lubricating oil, reflecting the fluidity and lubrication performance of lubricating oil at different temperatures. The viscosity of diesel oil should be within the appropriate range to ensure sufficient viscosity at high temperatures and good fluidity at low temperatures.

4.2 Flash point

Flash point refers to the lowest temperature at which the oil vapor and air mix and contact the flame when the lubricating oil is heated under specified conditions. The higher the flash point, the higher the safety of the lubricant.

4.3 Pour point

Pour point refers to the lowest temperature at which the lubricating oil is cooled to stop flowing under specified conditions. The lower the pour point, the better the fluidity of the lubricating oil at low temperatures.

4.4 Total Base Value (TBN)

The total base number refers to the content of alkaline substances in the lubricating oil, reflecting the ability of the lubricating oil to neutralize acidic substances. Diesel oil should have a high total base number to neutralize acidic substances generated by combustion and prevent corrosion inside the engine.

4.5 Sulfate ash

Sulfate ash refers to the residual ash content of lubricating oil after burning at high temperature. Too much sulfate ash will increase carbon accumulation and wear, so diesel oil should have a low sulfate ash content.

4.6 Antioxidant properties

Oxidation resistance refers to the ability of lubricating oil to resist oxidation deterioration under high temperature conditions. Diesel oil should have excellent oxidation resistance to extend the service life of the oil and keep its performance stable.

5. Selection and use of diesel oil

5.1 Choose the right diesel oil

Choosing the right diesel oil needs to consider the following factors:

5.1.1 Engine type

Different types of diesel engines have different requirements for lubricating oil, and the appropriate lubricating oil should be selected according to the recommendation of the engine manufacturer.

5.1.2 Working conditions

The operating conditions of diesel engines (such as ambient temperature, load, etc.) have an important impact on the selection of lubricating oil. Under high temperature and high load conditions, the lubricating oil with high viscosity and good high temperature stability should be selected, and the lubricating oil with low viscosity and good low temperature fluidity should be selected under low temperature conditions.

5.1.3 Service life

Select the appropriate lubricating oil according to the service life requirements of the engine. The engine with long oil change cycle should choose the lubricating oil with excellent oxidation resistance and high total base value.

5.2 Precautions for the use of diesel oil

5.2.1 Replace the lubricating oil regularly

Diesel lubricating oil will gradually deteriorate during use, and the lubricating oil should be replaced regularly according to the recommendation of the engine manufacturer to ensure the normal operation of the engine.

5.2.2 Check the oil content

Check the level of lubricating oil regularly to ensure that the amount of lubricating oil is within the appropriate range to avoid engine wear and damage caused by insufficient lubricating oil.

5.2.3 Keep lubricating oil clean

Avoid contamination of lubricating oil by dust, moisture and other impurities, and keep lubricating oil clean to ensure its stable performance.

5.2.4 Avoid mixing different types of lubricants

Different types of lubricating oil have different chemical compositions and properties, and mixing may lead to reduced lubricating oil performance, so mixing different types of lubricating oil should be avoided.

6. The development trend of diesel lubricants

With the continuous progress of technology and the improvement of environmental protection requirements, the development of diesel lubricants shows the following trends:

6.1 Environmentally friendly lubricants

Environmentally friendly lubricants use green and environmentally friendly raw materials to reduce environmental pollution. The development and application of bio-based oils and biodegradable additives have become a developing trend.

6.2 High efficiency lubricating oil

High efficiency lubricants have excellent lubrication properties, oxidation resistance and wear resistance to provide good lubrication over a wider range of temperatures and pressures. The development and application of synthetic lubricants and high-performance additives have become the development trend.

6.3 Long oil change cycle lubricants

The long oil change cycle lubricating oil has excellent oxidation resistance and high total base value, which can extend the service life of lubricating oil, reduce the number of oil changes, and improve the operation efficiency of the engine.

6.4 Multifunctional lubricating oil

Multi-functional lubricating oil not only has lubrication, cleaning, cooling and sealing functions, but also has a variety of functions such as corrosion resistance, oxidation resistance and wear resistance, which can comprehensively improve the performance and service life of the engine.

7. Test methods for diesel oil

The performance test of diesel lubricating oil includes physical test, chemical test and performance test.

7.1 Physical test

The physical test mainly includes the test of lubricating oil viscosity, flash point, pour point and other indicators.

7.1.1 Viscosity test

Viscosity testing usually uses a viscometer to measure the viscosity value of a lubricating oil at different temperatures to assess its fluidity and lubrication properties.

7.1.2 Flash point test

Flash point testing usually uses the open or closed cup method to measure the flash point temperature of the lubricating oil to assess its safety.

7.1.3 Pour point test

Pour point test The pour point temperature of lubricating oil is usually measured with a pour point tester to assess its low temperature fluidity.

7.2 Chemical test

Chemical testing mainly includes the composition analysis of lubricating oil, acid value, base value and other indicators of the test.

7.2.1 Component analysis

Composition analysis usually uses methods such as gas chromatography or liquid chromatography to determine the chemical composition of lubricating oils in order to evaluate their formulation and properties.

7.2.2 Acid value test

Acid value testing usually uses potentiometric titration to determine the acid value of lubricating oil to assess its acid content and corrosiveness.

7.2.3 Alkali test

Alkalinity testing usually uses potentiometric titration to determine the alkalinity of lubricating oils to assess the ability of medium and acidic substances.

7.3 Performance testing

The performance test mainly includes the wear resistance and oxidation resistance of lubricating oil.

7.3.1 Wear resistance test

Wear resistance testing usually uses methods such as four-ball machine or engine bench test to determine the wear resistance of lubricating oil to assess its ability to protect engine components.

7.3.2 Antioxidant performance test

Oxidation stability tests are usually used to determine the oxidation resistance of lubricating oils to assess their stability at high temperatures.

8. The development prospect of diesel lubricants

As an important protective agent of diesel engine, diesel oil has a wide application prospect. With the increasingly stringent environmental regulations and the continuous advancement of engine technology, the demand for diesel lubricants will continue to increase. In the future, environmentally friendly, efficient and multi-functional lubricating oil will become the development trend, and the performance and application range of diesel lubricating oil will be continuously improved.

In short, diesel lubricants play an important role in modern industry and transportation. By lubricating, cleaning, cooling and sealing engine components, diesel lubricants not only improve engine performance and life, but also save energy and reduce environmental pollution. With the continuous progress of science and technology, the performance and application range of diesel lubricating oil will continue to expand, providing strong support for the development of modern industry and transportation.