Supertest Petroleum Limited was a Canadian petroleum company that operated from 1923 to 1973. Its head office was in London, Ontario. It marketed itself as "Canada's All-Canadian Company", and was acquired by BP Canada in 1971.

John Gordon Thompson (1894-1982), an operator of automobile service centres and manufacturer of tire repair and gasoline pumps, formed London Automotive Service Ltd. with James D. Good on 13 March 1923. They purchased the assets of the Energy Oil Company for $10,000. Energy Oil Company owned a run-down gas station on Dundas St. E. in London, Ontario, a bulk storage plant in London, and two fuel delivery tank trucks. Thompson was elected president and Good was named vice-president and secretary/treasurer. They adopted "Supertest" as the trademark name of their gasoline.

On 23 May 1923, Supertest opened it first gasoline station at 362 Dundas Street E. Gas sold for 31 cents/gallon), and the station sold Mobiloil lubricants. The new company was not a refiner and sourced its gasoline and oil from Imperial Oil Ltd.

In 1924, Supertest opened subsidiary companies in Hamilton and Ottawa.

On 17 December 1925, Supertest Petroleum Corporation, Limited was incorporated. A subsidiary was formed in St. Thomas, Ontario. Bulk distributing plants were opened in Glencoe, Wingham and Seaforth, Ontario.

In 1926, Supertest bought the Ensign Oil Company of Montreal, opened a bulk distributing plant at Port Robinson, Ontario, and amalgamated all of the subsidiaries companies into one major company known as "Supertest Petroleum Corporation Limited". Supertest registered the trademark "Hi Compression" for its new gasoline.

In 1928, a tank ship, the M.S. Supertest, was put into operation. It made deliveries to Kingston, Ottawa and Montreal until it was sold shortly after World War II.

In 1932, Supertest registered the trademark "Wonder Gasoline".