ABSTRACT
Reuse of used lubricating oil has been known and practiced for several decades, especially with the use of these oils as burner fuel (Chapter 5). Until recently, the reliability of the re-refined product was an issue. However, the profusion of re-refining processes-each of which has something to add-has produced product oils that are able to meet base oil specifications and are used (when mixed with the necessary additives) for the desired lubricating purposes. As a result, the re-refined products have moved from being a less predictable mix of components to a highly refined high-value product (base oil) that is of sufficient quality to compare equally with the virgin base oil derived from petroleum sources and which can be used without further purification. This can also be translated into savings to the consumer buying a quart of recycled oil insofar as re-refining replaces the need for more of a valuable and decreasing virgin resource-which would lead to higher process costs for lubricating oil.
