This SAE Standard outlines the engine oil performance categories and classifications developed through the efforts of the Alliance of Automobile Manufacturers (Alliance), American Petroleum Institute (API), the American Society for Testing and Materials (ASTM), the Engine Manufacturers Association (EMA), International Lubricant Specification Advisory Committee (ILSAC), and SAE. The verbal descriptions by API and ASTM, along with prescribed test methods and limits are shown for active categories in Table 1 and obsolete categories in Table A1. Appendix A is a historical documentation of the obsolete categories. For purposes of this document, active categories are defined as those (a) for which the required test equipment and test support materials, including reference engine oils and reference fuels, are readily available, (b) for which ASTM or the test developer monitors precision for all tests, and (c) which are currently available for licensing by API EOLCS. The current processes for initiating new classifications were developed through the cooperative efforts of the Alliance, API, ASTM, EMA, ILSAC, and SAE. New ILSAC classifications are developed using the procedure defined in API 1509 Annex C. New API “C” categories are added using the procedure defined in API 1509 Annex D. New API “S” categories are added by the API Lubricants Group. This revision of SAE J183 had three key objectives: First, to explicitly render API Category CF obsolete. Many previous revisions had dealt with the obsolescence of Category CF by removing it from the document. The current document features text that echoes the format and approach used to describe all other obsolete categories, including in particular the provision of cautionary user language that should appear on labels for products claiming CF performance. Second, the format recently adopted by API to tabulate performance requirements of active “S” categories in document API 1509 has been adopted. However, because the new API format has eliminated an explicit listing of all performance parameters, such listings have been preserved as appendices to the main tables. Third, an editorial policy has been put in place to pare down 2.1.3.1. In general, this section will henceforth feature only tests adopted in the two most recent “C” and “S” categories. Additionally, minor editorial changes requested by reviewers have been applied.