The lubricity of gasoline

A study has been made of the lubricating propel ties of gasoline fuel. A co nventional HFRR diesel fuel lubricity tester has been modified to measure g asoline wear. Using this test equipment, a number of features of gasoline l ubricity have been investigated, including the comparative lubricating beha vior of gasoline, the influence of detergent additives and oxygenates on we ar and the wear behavior of a series of refinery streams employed in gasoli ne blending. The lubricity of a range of pure organic chemicals known to be present in g asoline has also been studied. From these measurements it has been shown th at, except for components such as dienes and diaromatics, the HFRR lubricat ing properties of most gasoline hydrocarbon constituents are broadly indepe ndent of chemical structure but depend significantly on viscosity. Using th ese measurements, predictive wear equations based on gasoline group analysi s have been developed. Because it has been found that viscosity plays a role in determining the we ar properties of gasoline, the elastohydrodynamic (EHD) film-forming and fr iction properties of gasoline have been measured and compared to those of d iesel fuels. This shows that the combination of gasoline's very low viscosi ty and low pressure-viscosity coefficient results in very thin EHD film thi ckness generation and also very low friction in full-film EHD conditions.