DEF Program Documents
2016 DEF Program Update
This document provides an explanation of the latest fee structure.
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.
Diesel Exhaust Fluid User Guide
This document provides an array of step-by-step instructions and screenshots to assist the user with the online application system and license maintenance.