Oil is an essential lubricant in your engine. It lets metal press against metal without damage. For example, it lubricates the pistons as they move up and down in the cylinders.
1 By the time of the Japanese surrender in August 1945, Korea was the second-most industrialized nation in Asia after Japan itself.  But the wartime mobilization of 1937-45 had reintroduced harsh measures to Japanese colonial rule, as Koreans were forced to work in Japanese factories and were sent as soldiers to the front.
Until 1876 Korea had seen herself as a subsidiary to China. The treaty with Japan caused great controversy and pro- and anti- Japanese factions emerged. In 1882 the Taewon'gun, a retired former leader of Korean, led a revolt against King Kojong and Queen Min.