Keywords INTRODUCTION Polyfunctional PIB Succinimide Type Engine Oil AdditivesThe physical and chemical properties of polyisobutylene (PIB) succinimide and polyisobutylene polysuccinimide type dispersants for engine oil have been studied. Differences in the enhancement or diminution of detergentdispersant, viscosityindex-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 detergentdispersant, 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 detergendispersant efficiency were demonstrated.additives, PIB succinimide, dispersant, detergent-dispersant, viscosity index, antiwear During the last 40 years or so, many processes have been developed for the production of ashless dispersants for use as oil additives. A large family of succinimide additives for engine oils has been synthesised.' By changing the production process or the chemical structure of the additives, an increase in detergent-dispersant efficiency and resistance against chemical or mechanical stress have been achieved (Table 1, overleaf).