Vacuum Oil was part of John D Rockefeller's US company the Standard Oil Trust. When the US Supreme Court ordered the dissolution of the Standard Oil Trust in 1911, its assets were acquired by one of the spin-off companies, the Standard Oil Company of New York, which eventually became Mobil Oil.
Although Mobil petrol brands did not appear in the UK until 1954, the trademark Mobiloil was used by Vacuum Oil in Britain as early as 1899. On December 1,1955, the company changed its name to the Mobil Oil Company Limited.
Records are vague, but indicate that whoever first suggested Mobiloil was motivated by the Latin word "mobilis" - meaning capable of being moved - and by the new horseless carriages that the product lubricated.