Blackstone Labs analyzes the contents of used motor oil to check how well engines wear over time. Earlier this month, the lab used its vast database of used oil analyses to study whether certain oil brands tend to contain more metal wear particles; the results might make you think twice before throwing down cash on performance racing oil.
Blackstone receives oil samples from thousands of people around the country interested in learning how well their engines are wearing over time.
Upon receiving samples, Blackstone sends the oil through a spectrometer to learn how much of that oil—in parts per million—is made up of wear elements.
Blackstone has thousands of reports showing wear particle concentrations of certain engines using certain oil types for certain oil drain intervals. In its July newsletter, the lab decided to use this data to compare different brands. And the findings suggest that buying expensive oil may not provide much of a benefit to engine longevity.
Blackstone Lab senior analyst Travis Heffelfinger looked at the Subaru EJ 2.5-liter engine, for which the lab has 5,234 reports completed. Those 5,234 reports are associated with oil samples that, on average, were used in the engine for 3,900 miles before draining. Travis then broke down those 5,234 reports by oil type, which owners tell Blackstone when submitting their samples.
According to his findings, for the wear metals, though, there’s not nearly as much variation. Iron is between 8 and 11 ppm all across the page, and copper is between 7 and 12 ppm for each set of averages. Other metals had even less variation, and no single oil type had the lowest level of all metals.
Because the oil drain intervals weren’t all exactly the same, Heffelfinger goes on, showing a bar chart of iron wear rate per 1,000 miles driven.
What the chart shows is that, even if you normalize the iron wear by mileages on the oil sample, the difference across the board—the lowest wear rate is 2.03 ppm per 1,000 miles, the highest is 2.58— is minuscule.
In other words, for every 1,000 miles, the Rotella T6 wears just over one half a part per million slower than the Royal Purple. As Heffelfinger writes in his report, that’s “…almost completely negligible. In a typical engine, a half a part per million of the oil in the sump is such a small quantity that you wouldn’t be able to see it without a microscope.”
These findings say more variation in wear levels from the type of engine, the time on the oil, the viscosity, the use the engine sees, etc. Whatever differences exist from oil brand to oil brand, it doesn’t see a lot of difference in terms of wear for most types of engines.
It’s worth noting that the data is only based solely on what owners and fleet managers have sent into Blackstone with various drain intervals. So there are some limitations. There might be a bigger difference in wear rate among brands if all of the oil samples had much higher mileage on them.
These findings did not disclose the driving styles or weather conditions associated with each sample; averaging the samples will help to limit the effect of these factors, but it’s not a perfect solution.
Still, looking at wear metal contents for different engines, and breaking results up by oil type is an interesting study. And despite its limitations, the report’s conclusion really isn’t too surprising. Engine oils have to meet certain specs to be API certified, and even the cheapest of modern oils are known to do a damn good job of keeping engine wear down.