The lubrication of surfaces by oils is a key aspect of many academic and industrial problems with significant financial implications. In this experiment we would like to extend our recent study to investigate the adsorption of the ZDTP from Palmitic acid (CH3 (CH2)14COOH on the Fe oxide surface (300 Å Fe film) layer both in the presence and absence of 1-hexadecylamine (CH3 (CH2)15NH2) surfactant additive. A series of surfactant concentrations (6 in total) will be used for two ZDTP concentrations (0.5 and 1 wt %). The layer thickness and the composition of the adsorbed film will be determined using polarised neutrons.