Diesel fuel dyeing

Off-road diesel is dyed to prevent illegal use of this tax-exempt fuel in on-road vehicles.

The U.S. Internal Revenue System defines red dye’s standard or quality requirements. The dye must be soluble in diesel fuel and have a distinct color that is visibly different from undyed diesel. The specific formulation and concentration of the dye are regulated to ensure that it can be easily detected in fuel inspections and will not affect the fuel’s performance while providing clear identification for compliance purposes.

The standard dye used for off-road diesel in the U.S. is Solvent Red 26. However, it can be replaced with a similar dye, Solvent Red 164.

IRS regulations require that tax-exempt diesel fuels (off-road), have a minimum level of red dye equivalent to 3.9 parts per