Experimental Investigation of Lubricant Oil Tribology and Cylinder Liner Wear in a Compression Ignition Engine Fueled with Biodiesel

This research investigates the impact on lubricating oil tribology and cylinder liner wear when used cooking oil-derived biodiesel is utilized as a substitute for mineral diesel during a 512-h engine endurance test. Lubricant oil properties are analyzed at regular intervals during the endurance test. The analysis revealed that biodiesel utilization results in a minor variation in lubricant oil properties compared to baseline diesel, mostly confined to the final stages of the endurance test. Kinematic viscosity was lower by 5% and density was higher by 1.5%. Flashpoint was lower by 4% for the biodiesel-fueled engine, whereas moisture content was 2.5% higher. However, the variation in oil properties was well within the specified oil critical limits and did not cause any operational problems. Optical emission spectroscopy is used to determine engine component wear particles in lubricating oil samples taken from both engines. Wear metal concentration was generally lower for the biodiesel-fueled engine except for higher copper, lead, and zinc traces. Cylinder liner surface wear is quantified by measuring the roughness parameters at three distinct regions: top dead center, mid-stroke region, and bottom dead center. Further, scanning electron microscopy is used to characterize the cylinder liner wear of biodiesel and diesel-fueled engines. Analysis of surface roughness parameters and SEM micrographs indicate that wear in the biodiesel-fueled engine is lower than in the diesel engine.