The initial process involved installing a fresh oil filter, and starting the car and running it for 5 minutes. This aim is to circulate the oil in the sump through the filter to remove contaminates and clean it up. Then, the filter is removed, changed with a fresh one, and the process repeated. After changing out ten filters in a row, the oil was compared to its state at the beginning of the test. While there were less particulate deposits, the color and consistency of the oil otherwise seemed virtually unchanged.
Modern oils consist of a complex mixture of additives, and these additives and the oil itself tend to degrade as the engine racks up running time. Heat cycles and combustion byproducts cause chemical changes to the oil’s makeup, and wear particles from moving parts all build up over time and reduce the oil’s performance. This is the primary reason why oil is changed regularly. Simply filtering out particles won’t actually do anything to restore the original condition of the oil itself. Filtering is still beneficial, of course, as particulate contaminants in oil will cause accelerated engine wear. However, there’s no simple way to turn old oil back into fresh oil simply by running it through a paper filter.
Read More: You Can’t Make Dirty Oil Clean Again With Fifty Filter Changes