Some people think petroleum is just fine the way it is; NewMarket thinks it needs a little something extra added to it to improve engine performance. The company is a holding entity for two petroleum additive subsidiaries: Afton Chemical (its primary business) and Ethyl Corporation. Afton Chemical manufactures petroleum additives used to improve the performance of gasoline, diesel, and other fuels and as a lubricant in motor oil, fluids, and grease. Ethyl's main product is the antiknock additive tetraethyl lead, though TEL has lost substantial ground in markets where unleaded gas is preferred or required.