Abstract: A lubricating oil input system includes a joiner, a first ignition advance vacuum tube connected between the joiner and distributor of an internal combustion engine, a second ignition advance vacuum tube connected between the joiner and carburetor of the engine, a connecting tube connected between the joiner and an oil tank which contains lubricating oil and cleaner. The system further includes a small tube disposed within the connecting tube, joiner and second ignition advance vacuum tube; a filter means disposed at the joint region of the oil tank and connecting tube; and a returning means connected to the first ignition advance vacuum tube abutting against the joiner, so that the lubricating oil is directed from the oil tank through the lubricating oil input system into the carburetor to be mixed with gasoline.