Heavy metal content in used engine oils depending on engine type and oil change interval

Abstract

The paper presents the results of the analysis of the content of selected heavy metals in used engine oils collected in car service stations during oil change. The main purpose of the research was to determine the difference in heavy metal content (Cr, Cu, Fe, Ni, Pb, Zn, Hg, Cd) depending on the engine type and oil change interval. The analysis comprised 80 samples of used engine oils obtained from passenger cars. The content of heavy metals was tested with use of the HDMaxine analyzer, operating on the basis of HDXRF (High-Definition X-Ray Fluorescence). Upon analyzing the differences in the average content of the examined elements, depending on the type of engine, it can be concluded that in oils coming from diesel engines the following elements showed a higher concentration – Cr (three times), Fe (1/3 times ), Ni (two times), Pb (1/2 times), whereas in oils coming from gasoline engines, only the average Cu content was higher (¾ times). Zinc had a comparable level of concentration. The multi-factor analysis of variance showed that in diesel engines the levels of Fe, Cr, Pb and Ni are statistically significantly different than in the reference group of gasoline engines. The study findings suggest that, depending on the engine type, the content of selected heavy metal elements in used oils varies. Therefore, to ensure proper handling of waste oils and reduce environmental risk, selective collection of used oils depending on the engine type may definitely be considered.

Keywords

• heavy metals
• lubricating oil analysis
• waste lubricant oil (wlo)