This work includes an assessment of the lubricity of Greek road diesel fuel of low sulfur content, and the effect of the addition of two different types of biodiesel which can be produced from raw materials abundant in the Mediterranean area.
In this study, a series of representative fuels of the Greek fuel market were tested. In some of them, the lubricity was measured three times, during a period of three months from the day of each sample was produced. In all cases a decrease of the wear scar diameter (WSD) was measured; this behaviour could be attributed to the oxidation reactions that take place during the storage period.
In order to monitor the effect of the addition of biodiesel on the lubricity of road diesel, biodiesels produced from sunflower oil and olive oil were used. The use of rape seed oil biodiesel as a diesel fuel substitute is a commercial event in Central Europe; in the United States the soybean oil biodiesel has been examined in detail. However, biodiesels prepared from other starting materials, such as sunflower oil and olive oil have not been examined extensively, although the above types of vegetable oils comprise interesting candidates for biodiesel production in Southern Europe.
The methylesters of sunflower oil and olive oil were added in the diesel fuels in concentrations varying from 0.25% to 10% vol. In all cases a noticeable decrease in WSD was observed, which eventually approached asymptotically a constant value.