This is an amended version of a 2008 published report titled “Evaluation of High Efficiency Oil Filters Final Report” (Publication # IWMB-2008-0020). This report was prepared by the California Department of Toxic Substances Control (DTSC) under a contract from the California Department of Resources Recycling and Recovery (CalRecycle). The text from the original 2008 report has been supplemented by the 2013 work on oil condition sensors and additional filtration technologies.