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The physical and chemical properties of polyisobutylene (PIB) succinimide and polyisobutylene polysuccinimide type dispers-ants for engine oil have been studied. Differences in the enhancement or diminution of detergent-dispersant, viscosity-index-improving, and antiwear effects were observed for different combinations of various functional additives and succinimide dispersants, depending on their chemical structure. Owing to the higher concentration of performance packages presently required for engine oils, the detrimental interactions of additives might increase, resulting in a reduction of the detergent-dispersant, viscosity-index-improving, and antiwear efficiency, as well as unfavourable gelation processes. Fourier-transform infrared spectrometry, gel permeation chromatography, and bench tests for screening engine oil additives were used to determined relationships between the properties of lubricating oils and the composition of additives. The advantages of well balanced and selected succinimide combinations in a performance package with high detergent-dispersant efficiency were demonstrated.

Additives of low and high molecular weight used as performance enhancers in engine oil formulations can interact through their polar functional groups to form associates and complexes. These often have a significant thickening effect that could substitute for viscosity and viscosity-index improvers. We therefore investigated the stability of these associates to thermal degradation, oxidation, and mechanical decomposition, in an attempt to seek information about their feasibility.

Engine oils today include detergency dispersancy additives to keep the engine clean, hold insolubles in dispersion, and neutralise acidic compounds. This paper describes the synthesis of a type of detergent-dispersant based on polyisobutenyl succinimides. The type and route of synthesis influence the molecular structure, performance, and applicability of the synthesised compounds. In particular, the average molecular weight of the polyolefin chain of the intermediates used has a decisive effect. A newly developed intermediate allows the preparation of polysuccinimides with a polymeric structure.

The paper shows the results of investigations into the interactions between different types of succinimides and zinc dialkyl dithiophosphates. Various properties of additives in oil solutions were tested and examined by various methods, in order to show the existence of interactions of various strengths between different types of succinimide and ZnDDP.