Description Ethyl hears you knocking and it hopes you let its products in. A subsidiary of NewMarket, Ethyl markets its gasoline performance additives and diesel cetane improver (which increases ignition quality in diesel fuel) throughout North America. It also makes anti-knock additive tetraethyl lead (TEL), which once was a primary product line for Ethyl but has seen diminishing returns since the U.S. Clean Air Act and others like it were put in place. NewMarket was formed in 2004 as a holding company for Ethyl and sister company Afton Chemical.