Normally, only the owner of the gasoline produced at an oxygenate blending operation must register as an oxygenate blender. If a common carrier blends gas in trucks that it owns it must meet all of the requirements for other oxygenate blenders. But see answer to Question 1 of the "General Requirements" section of this document.

If an oxygenate blender uses common carriers or its own trucks for splash blending it may register the entire fleet for any single covered areas as a facility and indicate the office where the truck blending operations are coordinated as the blending facility. The office so registered must be at the lowest level at which coordination occurs and geographically closest to each designated RFG area.(8/29/94)

This question and answer was 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)