Following the break-up of Standard Oil in 1911, the Standard Oil Company of New York, or Socony, was founded, along with 33 other successor companies. In 1920 the company registered the name "Mobiloil" as a trademark.
In 1931, Socony merged with Vacuum Oil to form Socony-Vacuum.
In 1955, Socony-Vacuum was renamed Socony Mobil Oil Company.
In 1963, it changed its trade name from "Mobilgas" to simply "Mobil," introducing a new logo. To celebrate its 100th anniversary in 1966, "Socony" was dropped from the corporate name.
link: MobilGas on Wikipedia
1940s Mobilgas ads