Founded in 1923, Ethyl Corp was formed by General Motors and Standard Oil of New Jersey (Esso). General Motors had the "use patent" for tetraethyllead (TEL) as an antiknock, based on the work of Thomas Midgley Jr., Charles Kettering, and later Charles Allen Thomas, and Esso had the patent for the manufacture of TEL. Since the patents affected the marketing of TEL, General Motors and ESSO formed Ethyl Corp; each parent company had a 50% stake in the new corporation. Since neither company had chemical plant experience, they hired Dupont to operate the manufacturing facilities. After patents ran out, Dupont started manufacture of TEL on their own, and Ethyl started running its own operations.