Low‐ and zero‐sulphated ash, phosphorus and sulphur anti‐wear additives for engine oils

Modern engine lubricant specifications include compositional constraints in terms of the permitted level of sulphated ash, phosphorus and sulphur (SAPS). This necessitates a reduction in the concentration of the additive zinc dialkyldithiophosphate (ZDDP) used in engine oils, and there is currently great interest in identifying anti‐wear additives that contain low or zero SAPS to partially or wholly replace ZDDP.