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.
Two months later, Korea was obliged to become a Japanese protectorate by the JapanâKorea Treaty of 1905 and the reforms were enacted, including the reduction of the Korean Army from 20,000 to 1,000 men by disbanding all garrisons in the provinces, retaining only a single garrison in the precincts of Seoul.