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DEF Program Documents

API Diesel Exhaust Fluid Certification Program Overview

This document provides an overview of the program and explanation of the requirements to become an API-licensed diesel exhaust fluid marketer and use the API DEF Certification Marks.

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Step-by-Step Guide for DEF Applicants and Licensees

This document provides an array of step-by-step instructions and screenshots to assist the user with the online application system and license maintenance.

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Branding Guide

This eleven-page guideline is intended to help licensees display and use the API Quality Marks properly. A downloadable Branding Guide is available in PDF format.

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