Sorry, I should have supplied some info on that.
A 15 parts per million (ppm) sulfur specification, known as Ultra Low Sulfur Diesel (ULSD), was phased in for highway diesel fuel from 2006-2010.
EPA Home > Transportation & Air Quality > Fuels and Fuel Additives > Diesel Fuel
http://www.epa.gov/otaq/fuels/dieselfuels/index.htm
Thanks!