Search Results

Effect of base stock material, especially polybutene, on two-cycle engine oil performance was studied. At first, visible smoke tests were conducted, using test oils of different base stocks. Polybutene showed the best performance among the test oils. Then, piston detergency tests were performed. Test oil of higher molecular weight polybutene showed poorer results. In addition, piston deposits were analyzed and it was found that polybutene molecular weight was increased during the test. Piston detergency was discussed in relation with the increase in viscosity caused by increase in molecular weight. Finally, engine startability tests were carried out. Good correlation with viscosity was found only in test oils of same mineral base stock concentration. The increase in engine start torque was attributed to increase in polybutene viscosity caused by selective evaporation of the lower molecular weight portion.

Soot accumulation in diesel engine crankcase is the dominant factor which governs engine oil drain interval. So, efficient soot elimination from crankcase oil can be a practical way to achieve drain interval extension. Combination of high performance oil filter and low soot dispersancy oil results in an effective measure to trap soot efficiently. In this paper, the behavior of newly developed high performance diesel engine oil having low soot dispersancy is reported. Prior to oil development, an evaluation method of soot dispersancy in oil was elaborated. Based on relative viscosity defined as ratio of soot containing oil viscosity to soot eliminated oil viscosity, dispersancy parameter was determined. Oil dispersancy evaluated on this parameter agreed with the results obtained from particle size analyzer. Secondly, a method to obtain oil filter soot trap rate to total soot contaminated into crankcase (trap rate) was established.