Investigations of the Tribological Effects of Engine Oil Dilution by Vegetable and Animal Fat Feedstock Biodiesel on Selected Surfaces

Biodiesels have become attractive alternative fuel to replace traditional fossil fuels. Biodiesels can be used in diesel engines with no major modification, but its use leads to some degree of engine oil dilution because of biodiesel leaking and scrapping to engine oil pan. Biodiesels can be made from vegetable and animal fat feedstocks. Therefore, the fatty acid methyl ester components of biodiesel may vary upon these sources of feedstock. In this thesis work, engine oil is diluted with vegetable (canola oil, peanut oil and soybean oil biodiesel) and animal (chicken fat) feedstock biodiesels at known percentages and these mixtures are tested in a pinon-disk tribometer. In-process friction force and temperature changes are observed and specific wear on the tested surface and dilution effects on viscosity are measured. The oxidative stability of diluted engine oils is also assessed by observation. Experimental results suggest that a higher fraction of palmitic and a lower fraction of linoleic acid contents of the biodiesel play a role for providing good lubricity when mixed with the engine oil in the tested condition and animal feedstock biodiesel perform better than that of vegetable feedstock biodiesel