There is a float in it, supported by a conical metal needle, the conical part is rubber, and supported by a hole leading to the upper part of the carburetor. If the float can't be reset, or the conical rubber part is worn or something is not tight, the oil will escape to the top and be discharged from the oil drain pipe. Maybe your oil drain pipe is blocked, so it will escape to the air filter. I don't know exactly. You can look at the pictures on the Internet or you can look at them yourself. Don't tear it down if you tear it down. It doesn't matter if you put a filter system in the fuel tank and carburetor. If it is dirty, open it and flush it with gasoline. Once you wash it, you don't need maintenance and cleaning. Generally, you don't need to wash it after a few years. ! !