There are no sulfur testing requirements downstream of the refiner/importer. However, to meet their affirmative defense to presumptive liability, parties that blend >15 ppm sulfur additives into diesel fuel subject to the 15 ppm sulfur standard must conduct a periodic sampling and sulfur testing program after the additive is added to the fuel (see 40 CFR 80.613(d).
Alternative affirmative defense requirements exist for blenders of >15 ppm anti-static additives that are based on a volume accounting reconciliation system (see 40 CFR 80.614).
Question and Answer was originally posted at Questions and Answers on the Clean Diesel Fuel Rules (PDF)(135 pp, 888 K, EPA420-B-06-010, July 2006, About PDF)