Refiners are required to determine the properties of each batch of RBOB they produce or import prior to the gasoline leaving the refinery. Under § 80.69(a)(4) the refiner is required to determine that the properties of the RBOB are sufficient to allow the downstream parties to establish, through sampling and testing, whether the RBOB has been altered or contaminated so that it will not meet the applicable RFG standard after the addition of the specified type of oxygenate.

If the refiner is complying with § 80.69(a)(6) and (7) [i.e. claiming the actual oxygen content blended by the downstream blender], then the refiner must have a contractual relationship with each downstream blender and conduct a quality assurance and testing program. If the refiner is complying with § 80.69(a)(8), in lieu of the contractual relationship and quality assurance requirements, he may make his compliance calculations based on specified, "worst case" assumptions about oxygen content.(7/1/94)

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)