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American Petroleum Institute
Engine Oil Licensing and Certification System
200 Massachusetts Avenue, NW
Washington, DC 20001-5571
Toll-free in the U.S. & Canada: 877-562-5187
Local & International: (+1) 202-682-8041
Contact Diesel Oil Matters for information requests or to arrange meetings with API personnel.
Engine Oil Toolkit
Whether you’re looking for information on the new oil standards, seeking guidance on switching your fleet to these next-generation oils, or searching for practical recommendations to bring CK-4 and FA-4 oils into your shop, you’ll find answers in the toolkit.