Among the key technologies currently being used for reducing emissions of oxides of nitrogen, Exhaust Gas Recirculation (EGR) has been found to be very effective for light duty diesel engines. However, EGR results in a sharp increase in particulate matter emissions in heavy-duty diesel engines. The presence of increased levels of particulate matter in the engine has led to increased wear of engine parts such as cylinder liners, piston rings, valve train system and bearings.
A statistically designed experiment was developed to examine the effects of soot contaminated engine oil on wear of engine components. A three-body wear machine was designed and developed to simulate and estimate the extent of wear. The three oil properties studied were phosphorous level, dispersant level and sulfonate substrate level. The above three variables were formulated at two levels: High (1) and Low (-1). This resulted in a 23 matrix (8 oil blends). The effect of soot was also studied and this resulted in a 24 factorial experiment.
Results show that diesel soot, interacts with oil additives reducing the oil's anti-wear properties possibly by abrasive wear mechanism. Statistical analysis (GLM) showed that the phosphorus level plays a dominant role on the oil's wear performance.
The effect of dispersant level was not significant, though on an average, higher dispersant levels reduced wear. The effect of sulfonate was negligible within the range of concentrations tested.