Diesel fuel is another name for petroleum distillate fuel oil, which is sold for use in motor vehicles that use the compression ignition engine. Diesel is named after its inventor, German engineer Rudolf Diesel, who patented his original design in 1892. At petroleum refineries, diesel is refined from crude oil. Most diesel fuel sold in the United States contained high quantities of sulfur before 2006. However, as we know, sulfur in diesel fuel produces air pollution emissions that are harmful to human health. Therefore, it was asked by the U.S. Environmental Protection Agency to reduce the sulfur content of diesel fuel sold for use in the United States.