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  List of Reformulated Gasoline and Anti-Dumping Questions and Answers: July 1, 1994 through November 10, 1997 (pdf) (2.98 MB, July 2003)