I have an oil gas mixture leak that runs down port side of drive shaft housing on outside it is black in color and usually appears after shutting off motor. any ideas where leak is coming from ? It's a 1996 75 hp Force. Compression test is 125 127 128 don't think it's a head gasket leak. Motor runs fine. Your thoughts. Don't want to do a tear down without some input from others. Usually wipe it off with a rag twice when i get it home and doesn't appear again till i use motor again, It's just one of those things that sets in the back of you mind and says ????????