Low sulfur, phosphorus and metal free antiwear additives: Synergistic action of salicylaldehyde N(4)-phenylthiosemicarbazones and its different derivatives with Vanlube 289 additive

► The article presents antiwear properties of salicylaldehyde N(4)-phenyl thiosemicarbazones. ► Their synergistic interaction with organic borate esters has also been studied. ► The synergistic formulations are better antiwear additives than ZDDP/borate esters. ► These formulations are eco-friendly.