Lubricity assessment of gasoline fuels

•Comparison of modern types of gasoline fuels focused on their lubricity value.•Model prediction of the lubricity based on the other fuel and tribological properties.•We estimated the repeatability of commercial gasoline fuels.•Wear analysis using electron Scanning Microscopy and detection of chlorine in fuels.•The effect of refinery streams on the lubricity of modern commercial gasoline fuels.

This paper presents the lubricity measurements of the three commercial gasoline types, unleaded gasoline (95 RON), new super or LRP (96 RON) and super unleaded gasoline (98 RON) and the effects of various physico-chemical properties on lubricity. The results indicate that the nature of the fuel is an important factor for the lubrication properties of each type of gasoline fuel. The potassium content takes an active part in this and the amount that is added to the fuel doesn't seem to affect the final result of CWSD1.4 proportionally. A careful statistical approach to the data identified that, the composition, the sulfur and nitrogen contents, the oxygen content that is mainly contributed from the MTBE content and the viscosity, do affect the lubricity but in a different degree for each type of fuel. This differentiation of the properties' effect on lubricity, reinforces the idea of the complicated wear mechanism that takes place under the specific conditions of the experiments and the important role of the compositional characteristics of the fuel. Oxygen content and MTBE seem to maintain or even increase the wear mechanism. Chlorine was also detected on the metal surface of the specimens after scanning with electron microscopy (SEM).