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6
Alternative Processing
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6.1 INTRODUCTION
Used lubricating oil (Chapter 3) is exactly what its name implies—any petroleum-
based 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-rened 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 ...