The dye provisions in § 80.520(b) do not directly require that dye be added at the refinery gate. The dye provision establishes a presumption that fuel is highway fuel if it is not dyed. As a result, in the past refiners have added visible evidence of the dye to all fuel that did not meet the highway standard, so that it would not be treated as subject to the highway standard. In the 2004 nonroad rule, EPA dramatically limited the role that dyeing plays under the regulations, to allow for more fungible distribution of diesel fuel.
After June 1, 2010, there is no longer any presumption that undyed fuel is highway fuel. Therefore after that date there is no need for refiners to dye fuel to make sure it is not considered highway fuel subject to the highway standards. At that point, EPA will rely on the designation provisions to identify what the fuel is and what sulfur standard applies.
Prior to June 1, 2010, only a limited subset of diesel fuel must be dyed (in the distribution system above the truck rack; fuel must still be dyed when leaving the truck rack to meet IRS requirements) to avoid the presumption that it is highway fuel. From the effective date of the nonroad diesel final rule (August 30, 2004) until June 1, 2010, only heating oil and high sulfur NRLM must be dyed red at the refinery gate to avoid being subject to the highway and nonroad sulfur standards. Prior to August 30, 2004, all diesel fuel which did not meet the applicable requirements for highway diesel fuel was required to be dyed red at the refinery gate to avoid being subject to the highway standard. After June 1, 2010, there are no EPA requirements to dye any diesel fuel at the refinery gate. Similarly, there are no EPA requirements for diesel fuel produced downstream of the refinery such as transmix or segregated interface-derived diesel fuel to be dyed upstream of the terminal. In all cases, highway fuel is required to be free of visible evidence of red dye.
Any diesel fuel which is required to contain the fuel marker solvent yellow 124 (heating oil beginning 6/1/2006 and LM diesel fuel 6/1/2010 - 5/31/2012; see § 80.510) is also required to contain visible evidence of dye solvent red 124. The fuel marker and associated red dye requirements apply prior to the distribution from a truck loading terminal. The Internal Revenue Service requires that untaxed diesel fuel (nonroad, locomotive, & marine, & heating oil) be dyed before leaving the terminal. Thus, 15 ppm NRLM can be dyed just prior to leaving the terminal.
Question and Answer was originally posted at Questions and Answers on the Clean Diesel Fuel Rules (PDF)(135 pp, 888 K, EPA420-B-06-010, July 2006, About PDF)