What are the functions of ashless dispersants?

What are the functions of ashless dispersants?

1. Solubilization: Some oxidation products polymerize and mix with condensate to form engine sludge, increasing carbon deposits in the engine. This sludge adheres to the fuel tank, preventing the fuel pump from drawing in fuel and thus clogging the filter. Succinimid dispersants can form micelles with oil-insoluble carbon deposits and sludge, and complex with them to form an oil-soluble liquid, dispersing it in the oil. The solubilization effect of dispersants is excellent, about 10 times better than that of detergents.

2. Dispersion: Dispersants provide larger oil-soluble groups than detergents, effectively preventing the aggregation of carbon deposits and colloidal substances.

Currently, polyamine-based succinimides are the mainstream dispersant products, accounting for more than 80% of the total dispersant usage. The chemical structure consists of lipophilic groups, polar groups, and a linking group. This structure readily forms micelles in lubricating oils, ensuring strong solubilization of initial liquid oxidation products and excellent colloidal dispersion of solid particles such as carbon deposits and soot. This effectively guarantees the low-temperature dispersion performance of internal combustion engine oils and particularly solves the problem of low-temperature sludge in gasoline engine oils.

Gasoline engine oils with added dispersants show reduced sludge in the crankcase after prolonged operation and oil changes. They also improve the dispersion and solubilization of soot and lubricating oil oxidation products generated at high temperatures. Especially when combined with metal detergents, they have a synergistic effect, improving the quality of the lubricating oil while reducing the amount of additives required.

Adding dispersants not only improves the detergency and dispersibility of marine cylinder oils but also significantly reduces the amount of highly alkaline additives needed, lowering costs. They are increasingly being used in the production of marine cylinder oils. Two-stroke gasoline engine oils are mixtures of lubricating oil and fuel oil that undergo combustion. Excessive amounts of metal detergents and antioxidants can easily lead to wear and ring adhesion. Using special dispersants or a combination of detergents can prevent these problems.

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