Effects of detergents with different base values on lubricating oil performance

Lubricating oil metal detergent is one of the main additives for internal combustion engine oil, mainly including sulfonates, sulfurized alkylphenol salts, alkyl salicylates, etc., and its usage accounts for about 20% of the total usage of lubricating oil additives. Metal detergent has neutralizing, washing, dispersing and solubilizing effects, which directly affect the quality of internal combustion engine oil, especially in cleaning engine carbon deposits and extending engine life.

Most detergents have a certain base value, so they can neutralize the acidic substances produced by oxidation during the use of lubricating oil, and the base value has a significant effect on the performance of the detergent. According to the base value, detergents can be divided into several categories such as low base value, medium base value, high base value, and ultra-high base value detergents. With the deepening of research, people's understanding of the base value of detergents has been continuously deepened. For example, Buyanovskii et al. studied the tribological properties of metal detergents with different base values and found that with the increase of the base value of the detergent, the anti-wear performance of calcium alkylbenzene sulfonate was improved. Further research shows that high-base metal detergents have a certain effect on the tribological properties of oil products. On the surface of the friction pair, high-base metal detergents can form a protective film mainly composed of calcium carbonate and calcium oxide, which significantly improves the anti-wear and friction reduction properties of the lubricating oil, while medium and low-base metal detergents cannot form a protective film.

At present, the research on metal detergents mainly focuses on the effects of metal detergents of different types, structures, and colloidal particle sizes on the high-temperature detergency of engine oils, and the effects of detergents of different structures on the water separation performance of diesel engine oils. Among various metal detergents, alkylbenzene sulfonates have become the main force in the market due to their excellent cost-effectiveness. Therefore, it is of great significance to deeply study the effects of alkylbenzene sulfonate detergents with different base values on the performance of lubricating oils. In this paper, the internal combustion engine oil coking test method, the marine oil-water separation performance determination method and the four-ball machine test method are used to study the high-temperature detergency, oil-water separation performance and extreme pressure and anti-wear performance of lubricating oil samples (referred to as oil samples) added with different base number calcium alkylbenzene sulfonate, and explore the influence of detergents with different base numbers on the performance of lubricating oil.