In general, the maximum oxygen content for RFG that is not designated as VOC-controlled is 3.5 weight% oxygen. However, under the terms of the § 211(f) "Sun" waiver, MTBE blends are restricted to 15 volume% (or approximately 2.7 weight% oxygen). Refiners may ship RFG designated as VOC-controlled only if the RFG has an oxygen content of 1.5 to 2.7 weight%.
For those areas with state oxygenated gasoline programs under § 211(m) of the Act, EPA has granted a "blending tolerance" which allows upstream parties to introduce ethers of up to 2.9 weight% oxygen. The reason for this tolerance was to address the slight dilution of oxygen content in the distribution system and to ensure downstream compliance with the 2.7 weight % oxygen content for oxygenated gasoline program areas under § 211(m). This "blending tolerance" only applies in oxygenated gasoline program areas. For those oxygenated gasoline areas that are also RFG areas, the blending tolerance would only apply during the oxygenated gasoline control season (i.e. there is no "blending tolerance" in these areas during the VOC-controlled season or for VOC-controlled RFG).(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)