Been noticing some oily residue behind me when I'm idling or just after I shut off the engine. I don't see anything inside the motor housing to suggest it is leaking...only thing I can see is some older looking grease or oil residue below the housing, could this be what I'm seeing? The motor is my 1968 20hp Johnson. I'm not seeing any loss of gas from the tank other than regular running. I had a full tank (6gal) and ran it the last 3 days ending up with about 3gal left...????