ABSTRACT
Used lubricating oil (Chapter 3) is exactly what its name implies-any petroleumbased lubricating oil or synthetic lubricating oil that has been used. During normal use, impurities such as dirt, metal scrapings, water, or chemicals can get mixed in with the oil so that, in time, the oil no longer performs well. Eventually, this used oil must be replaced with virgin lubricating oil or re-refined lubricating oil to do the job correctly because used lubricating oil (1) is insoluble, persistent, and could contain toxic chemicals and heavy metals; (2) is slow to degrade; and (3) is a major source of oil contamination of waterways and can result in the pollution of drinking water sources.
