Dispersant additives: definition, principle of action, chemical composition and application in motor oils
2026-11-05
Dispersants - important functional components of motor oil formulations. They are designed to control the aggregation of soot, oxidation products and other insoluble contaminants, helping to maintain their even distribution in the oil and reduce the risk of sludge and deposit formation. Correct choice of type, molecular structure and concentrationDispersants allows motor oil manufacturers to improve detergency, oil performance stability and engine protection.
For Lubricant Manufacturers Dispersant additives affect not only engine cleanliness, but also viscosity stability, compatibility of various formulation components and finished product performance. Therefore, understanding the chemical composition, mechanism of action and principles for selecting dispersant additives is of great importance in the development of high-performance motor oils.
1. What are dispersants and what problems do they solve?
During engine operation, soot, fuel oxidation products, oil aging products and other insoluble substances gradually enter the engine oil. If such fine particles are not maintained in a stable dispersed state, they can interact with each other, combine and form larger aggregates or sludge.
As contaminants accumulate, oil viscosity may increase, sludge deposits may form, and the cleanliness of internal engine parts may deteriorate.
The main task of dispersing additives is to adsorb on the surface of insoluble particles and stabilize them, reducing the likelihood of aggregation and subsequent precipitation.
Unlike mechanical filtration, dispersant additives do not directly remove contaminants from the oil. They help keep small particles suspended in the oil environment so they can travel with the circulating oil and be removed or controlled by the engine filtration system.
From a formulation development point of view, dispersant additives solve three main problems:
- Soot dispersion:Reduce the tendency of diesel soot particles to aggregate and help control soot-induced increases in oil viscosity.
- Sludge control:prevent the aggregation of oxidation products and other insoluble substances, reducing the risk of sludge formation and accumulation.
- Maintaining oil purity and stability:help keep contaminants dispersed and improve oil stability during operation.
Thus, dispersant additives are an important component of modern motor oil formulations, especially oils for diesel engines and engines operating under high loads.
2. Operating principle and main advantages Dispersing additives
Molecular Structure Dispersants typically have two main parts: a polar group that can interact with the surface of contaminants, and an oil-soluble hydrocarbon chain that is compatible with the base oil.
This structure allows dispersant additives to form an adsorption layer on the surface of the particles, which reduces the likelihood of their re-combination.
The mechanism of action can be divided into three stages:
| Stage | Mechanism of action Dispersants | Implications for oil formulation |
| Particle adsorption | Polar groups interact with the surface of soot and oxidation products | Improves additive binding to contaminants |
| Particle stabilization | Oil-soluble molecular chains create a spatial barrier that prevents particles from approaching each other | Reduces risk of aggregation and sludge formation |
| Maintaining variance | Particles remain dispersed during oil circulation | Improves oil purity and operational stability |
From a formulation development perspective, quality dispersants provide the following benefits.
1. Improved soot dispersion
During operation of a diesel engine, soot enters the engine oil and gradually accumulates in it. Thanks to adsorption and spatial stabilization, dispersant additives help reduce the aggregation of soot particles and reduce its negative impact on the rheological properties of the oil.
2. Control of sludge and deposit formation
At high temperatures and under conditions of oxidation of motor oil, various insoluble substances are formed. Dispersing additives help keep them dispersed, reducing their tendency to aggregate and form sludge.
3. Increasing formulation stability
The correct choice of dispersant additives helps to increase the stability of the dispersed contaminant system. However, the final result also depends on the properties of the base oil, the type of detergent additives, antioxidants and the compatibility of other components of the formulation.
4. Development of high-performance motor oils
Based on engine type, operating conditions, and finished product performance requirements, lubricant manufacturers can adjust the type and concentration of dispersant additives to optimize detergency and overall oil performance.
3. What is the chemical composition of dispersant additives for motor oils?
In the modern lubricants industry, the most common ashless dispersant components include polyis-butenylsuccinimide-based compounds.
One commonly used type is polyisobutenylsuccinimide (PIBSI). Its molecular structure typically consists of an oil-soluble polyisobutene chain and a polar succinimide group.
These two structural parts perform different functions:
- Polyisobutene chain (PIB):provides good solubility in oil and creates a spatial barrier that reduces the tendency of particles to aggregate.
- Succinimide group:contains polar centers due to which dispersant additives interact with soot particles and other insoluble contaminants.
Depending on the molecular structure and modification methods, dispersant additives can be produced in several versions.
| Type Dispersants | Main structural features | Typical Applications |
| Polyisobutenylsuccinimide (PIBSI) | Consists of a polyisobutene chain and a polar succinimide group | Soot dispersion and sludge control in motor oils |
| High molecular weight polyisobutenylsuccinimide | Has longer polyisobutene chains; molecular weight and structure are controlled during product development | Formulations of high-performance motor and diesel oils |
| Borated polyisobutenylsuccinimide | Obtained by introducing boron into the structure of traditional PIBSI | Used in formulations where additional optimization of dispersing and other performance characteristics is required |
| Other modified ashless dispersants | The structure is modified through various chemical modifications to adjust polarity, oil solubility and compatibility | Specialized lubricant formulations |
It should be taken into account that the characteristics of differentDispersantscannot be assessed solely by molecular weight or the presence of boration. For an objective assessment, it is necessary to take into account the structure of the starting material, synthesis technology, quality indicators of the finished product and test results in a specific formulation.
4. How are dispersant additives for motor oils classified?
In terms of chemical structure and use in motor oil formulations, dispersant additives can be classified according to basic structure, molecular weight and mode of modification.
| Classification criterion | Main categories | Structural features and application |
| Based on basic chemical structure | Polyisobutenylsuccinimide | Contains an oil-soluble chain and a polar group; refers to common types of ashless dispersant additives |
| By molecular weight | Standard and High Molecular Weight | Molecular weight and chain length affect oil solubility, dispersing properties and viscosity of the formulation |
| By modification method | Unborated Dispersants and Borated Dispersants | Boriding and other modification methods allow you to change the chemical structure and performance characteristics of the product |
| By form of application | Individual additives and additive package components | The choice depends on the composition of the formulation and the requirements of the lubricant manufacturer |
Polyisobutenylsuccinimide products occupy an important place among ashless dispersant additives. When developing engine oils with increased soot dispersancy and sludge control requirements, special attention should be paid to the molecular structure, molecular weight and actual dispersant characteristics of the product.
5. How to choose suitable dispersant additives for motor oil?
For lubricant manufacturers and additive package companies, the choice of dispersant additives should not be based solely on the product name or one single indicator. It is necessary to take into account the requirements for the finished oil, the type of base oil and the features of the entire formulation.
1. Selection based on the type of engine oil
Operating conditions and the composition of contaminants vary depending on the type of engine.
- Diesel engine oils:The focus should be on the ability to disperse soot, control sludge formation and limit viscosity growth.
- Oils for gasoline engines:Control of high-temperature oxidation products, low-temperature sludge, and keeping internal engine parts clean are important.
- Oils for heavy-duty engines:Applicability Dispersant additives should be evaluated based on operating conditions, contamination levels, and oil performance requirements.
2. Selection based on molecular structure
Polyisobutene chain length, polar groups and molecular weight influence the characteristics of dispersants.
Depending on the formulation requirements, standard PIBSI, high molecular weight PIBSI and borated PIBSI can be compared and the appropriate product can be determined based on the test results.
3. Compatible with base oil and other additives
Dispersants must be compatible with the base oil, detergents, antioxidants and other functional components.
When developing a formulation, it is necessary to evaluate storage stability, low temperature properties, viscosity changes, and possible interactions between various components. You cannot judge the characteristics of the finished oil only by the properties of one additive.
4. Testing as part of the finished recipe
Depending on the requirements for the target engine oil, it is recommended to conduct comprehensive tests, paying special attention to the following indicators:
- Dispersing ability in relation to soot and change in viscosity under its influence;
- Control of sludge and deposit formation;
- Compatible with base oil and other components of the additive package;
- Storage stability and low temperature properties;
- Compliance with the requirements for the target category of engine oil and the results of the prescribed tests.
There is no universal dosage standard for dispersing additives for all formulations. The recommended concentration should be determined based on the supplier's technical documentation (TDS) and test results of the finished formulation.
6. Main factors affecting the quality of dispersants
For additive manufacturers, the quality of the finished product depends not only on the development of the chemical structure, but also on the control of raw materials, reaction conditions and control of production processes.
Key factors include:
Raw material quality control:The quality of polyisobutene, maleic anhydride and amine raw materials affects the synthesis process and the characteristics of the finished product.
Process control:it is necessary to maintain stable temperature and reaction duration, ratio of starting components and other technological parameters. This is important to ensure reproducibility of structure and product quality.
Monitoring key indicators:In accordance with the specification of a particular product, nitrogen content, boron content (for borated products), viscosity, water content and other necessary indicators are checked.
Stability between batches:Incoming inspection of raw materials, monitoring of production processes and testing of finished products help reduce quality variations between individual batches.
For lubricant manufacturers, consistent product quality and reliable technical support are important criteria for long-term supplier selection.
7. Main directions of development Dispersant additives
As the engine industry develops, environmental requirements become more stringent and quality standards for lubricants rise, the requirements for ash-free dispersant additives become increasingly higher.
In the future, the development of dispersant additives will be focused on several areas:
- Increasing the efficiency of soot dispersion:optimization of molecular structure and dispersing properties for working with soot formed during the operation of diesel engines.
- Compatible with high performance formulations:development of dispersant additives with good compatibility with various base oils, detergent additives and other functional components.
- Molecular structure optimization:regulation of polyisobutene chains, polar groups and chemical modification methods to improve complex product characteristics.
- Improvement of production processes:strengthening control of raw materials, synthesis parameters and quality of finished products to improve consistency between batches.
For lubricant and additive manufacturers, continuous improvement of product molecular structure and production technologies is an important basis for meeting diverse customer requirements.
8. Lansheng - development and production of additives for lubricants
Lansheng (Jinzhou) Chemistry LLC was founded in April 2018. The company specializes in the development, production and sales of lubricant additives, and provides products and technical support to lubricant manufacturers in China and abroad.
The company's production base occupies approximately 46,667 m² and is equipped with five production lines. The annual production capacity is approximately 60,000 tons. The team consists of 9 research and development specialists and 12 engineering and technical specialists. Production processes are organized according to a closed scheme using intelligent control systems, which helps to increase production efficiency and stability of product quality.
The company's product range includes detergent additives, ashless dispersant additives, additive packages and other functional components for various lubricant formulations.
In the direction of ash-free dispersant additives, the company pays attention to the structure of polyisobutenylsuccinimide compounds, their production technology and performance characteristics. The main areas of application of the products are related to soot dispersion, sludge control and adaptation to various motor oil formulations.
We pay special attention to product quality, stability of supply and the real needs of customers, striving to build long-term cooperation with lubricant manufacturers and enterprises producing additive packages.
Looking for Dispersant Additives for your formulation?
Contact Lansheng (Jinzhou) Chemicals LLC to discuss the type of engine oil, base oil system used and performance requirements. We are ready to provide relevant product information and technical support.
Frequently asked questions (FAQ)
Question 1. What are dispersant additives for motor oils?
Dispersant additives are functional components of motor oils designed to adsorb and stabilize soot, oxidation products and other insoluble contaminants. They reduce particle aggregation and help control sludge and deposit formation.
Question 2. What is the basic chemical composition of dispersants?
Common types of ashless dispersants include polyisobutenyl succinimide (PIBSI), high molecular weight PIBSI, and borated PIBSI. Their typical molecular structure includes an oil-soluble polyisobutene chain and a polar succinimide group.
Question 3. How do dispersant additives differ from detergent additives?
These components perform different functions, but are usually used together in motor oil formulations. Dispersants help keep soot and other insoluble contaminants dispersed. Detergent additives are primarily involved in neutralizing acidic products, controlling high temperature deposits and maintaining engine cleanliness.
Question 4. Why are dispersant additives used in diesel engine oils?
When a diesel engine is running, soot gets into the engine oil. Dispersant additives help reduce the aggregation of soot particles and reduce its negative impact on oil viscosity and stability.
Question 5. How to determine the dosage of dispersant additives in motor oil?
Dosage depends on the specific brandDispersants, requirements for the finished oil, type of base oil and combination with other components of the formulation. It is recommended that the range specified in the TDS technical documentation be used as a starting point, and the final concentration determined from tests for soot dispersion, viscosity change, sludge control and stability of the finished formulation.
