Are there different reporting requirements for refiners, importers and oxygenate blenders?

Yes. See § 80.75 of the regulations.(7/1/94)

This question and answer was originally posted at Consolidated List of Reformulated Gasoline and Anti-Dumping Questions and Answers: July 1, 1994 through November 10, 1997 (PDF)(333 pp, 18.17 MB, EPA420-R-03-009, July 2003, About PDF)