sorry if this has been gone over before but oil and air are to short for seaching. any-who i cant seem to find a replacement filter at all for this thing so is this thing a permanent filter that you just keep cleaning forever? also since all i can read of whats left to the label on it is gasoline on one line and kerosene on another line. what do i use to clean it? how do i clean it? and what oil and how much oil do i put back in? i have a manual for the tractor and it just says to fill to mark every 50hrs.