History (from Wikipedia, verifiable from Exxon-Mobil's website)
The Vacuum Oil Company was incorporated in 1866 by Matthew Ewing and Hiram Bond Everest.[1] In 1879, Standard Oil Company, headed by John D. Rockefeller, purchased a three-quarter interest in Vacuum. During the ensuing years, Rockefeller organized his various oil holdings into the Standard Oil Trust, with headquarters in New York. Standard Oil Company of New York (Socony) founded with dissolution of Standard Oil in 1911. In 1930, Vacuum acquired Wadham's Oil Company and the White Star Refining Company.
In 1931, Socony acquired all the assets of Vacuum Oil Co. and changed its name to Socony-Vacuum Corporation. In 1933, Socony-Vacuum and Standard Oil of New Jersey (later to become known as Esso, then Exxon) merged their Far East facilities and interests into a 50-50 venture called Standard-Vacuum Oil Co., or Stanvac. In 1934, Socony-Vacuum Corp. changed its name to Socony-Vacuum Oil Co., Inc.
In 1955, the name was changed to Socony Mobil Oil Company, Inc. In 1966, there was a further change of name to the Mobil Oil Corporation.