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.
Japanese rule of Korea was the outcome of a process that began with the JapanâKorea Treaty of 1876, whereby a complex coalition of Meiji government, military, and business officials sought to integrate Korea both politically and economically into the Empire of Japan.