Abstract:In order to study the effect of biodiesel on diesel engine oil,methyl oleate of 10% and 20% at weight were added into diesel engine oil respectively.The effects of methyl oleate on the viscosity,acidity and npentane insoluble matter content of diesel engine oil before and after oxidation were studied.The percentage of different methyl oleate content on the physical and chemical properties of diesel engine oil was quantified,and the overall percentage of effect of different methyl oleate content on thermal oxidation properties of diesel engine oil was obtained.The results show that the formation of macromolecule polymers,acidic substances and npentane insoluble substances in diesel engine oil samples is accelerated after the addition of methyl oleate,which causes the increase of viscosity and acidity.Methyl oleate has the greatest impact on the acidity of diesel engine oil,the second is on the viscosity,and the least is on the insoluble substance content.This indicates that the formation of acidic substances is easy and fast after the addition of methyl oleate,which is the main reason for the oxidation deterioration of diesel oil.The more methyl oleate is added,the greater the influence of methyl oleate on the thermal oxidation performance of diesel oil is.This is because with the gradual addition of methyl oleate,its dilution will aggravate the performance degradation of diesel oil.