The impact of a fatty triamine (Triameen YT) additive was investigated on the friction performance and stability of molybdenum dithiocarbamate (MoDTC) in the formulations containing polyalphaolefin synthetic base oil (PAO) and zinc dialkyldithiophosphate (ZDDP). Triamine has no significant effect when mixed with MoDTC and ZDDP, but it improves the performance of MoDTC alone. However, in the MoDTC—Triamine—PAO solutions, a chemical reaction easily occurred and a reddish precipitate was formed upon storage. According to IR, XPS, TEM, and XAS characterizations, this precipitate is poorly crystalline layered alkylammonium oxothiomolybdate. Formation of the precipitate impaired the tribological performance by decreasing the number of active species delivered at the sliding contact interface. However, low friction coefficients were recovered by redispersion of the precipitate in PAO.
