Conoco was the trade name for gasoline and other products sold, and for a chain of service stations operated, by the Continental Oil Company (later Conoco Inc.) from 1929 to 2002, when the company merged with Phillips Petroleum Company to form ConocoPhillips.
This triangular logo was derived from one previously used by the Marland Oil Company when it acquired Continental Oil Co. in 1929. This looked a bit like the 1897 YMCA logo. It remained in use until 1970.
This more modern, stylized logo was introduced in 1970 and used until the 2002 merger with Phillips. Despite this, Conoco stations are still around, and still use this logo.