Lubricating Performance and Antiwear Mechanism of Tallow Diamine Dioleates as an Additive of Engine Oil

Abstract Low/zero-SAPS (sulfated ash, phosphorus, sulfur) additives are emerging as a critical development direction. The function of tallow diamine dioleates (CAS 61791-53-5) as an additive of engine oil was evaluated under two typical conditions. The results demonstrate that its polar functional groups form a protective film on metal surfaces, thereby mitigating friction and oxidation-induced fatigue wear. However, the carboxylic acids produced by tallow diamine dioleates (TDO) hydrolysis diminish their antioxidation effectiveness under the elevated localized temperatures induced by high load. As an additive of engine oil, the concentration of TDO should be determined based on practical application. These findings provide a novel approach for engine oil formulation.