According to the 2015 Oil Survey of Fleet Maintenance readers, 32.5 percent of respondents say they conduct an oil analysis on engine lubricants every oil change. About 27.4 percent say they never conduct an oil analysis on engine lubricants, while approximately 21.8 percent say they do so when there is a concern. Less than 5 percent say they conduct an oil analysis on engine lubricants when extending service intervals.