The regulations finalized with the nonroad rule modified the sulfur test method requirements. Instead of a designated method, there are now simply performance-based requirements that must be met, allowing the use of multiple test methods (see § 80.580 and 69 FR 39184).

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)