Engine oil is a type of chemical agent that is necessary for stable machine operation over a long period of time. It is a product that is manufactured mainly for the purpose of putting it into engines that are necessary for driving automobiles and ships. By adding an appropriate amount of engine oil, it is expected to reduce the frictional resistance and frictional heat generated by a high-speed rotating engine. I can do it. There are different types of engine oils depending on the engine speed and load, and this difference applies to the strength and heat resistance of the oil. If engine oil continues to be used, it will be oxidized and deteriorated by the heat generated by the engine, so it must be replaced periodically.