oil or gas leak after oil change on yamaha 4 stroke 15 horse

[joemook]

i just changed oil and lower unit gear oil on my 15 4 stroke ---i am seeing oil or gas in the water behind the motor--i feel i closed the drain holes properly--there seems to be black marks of exhaust residue where exhaust comes out in motor rear---if i put in a little too much oil when i changed it could this be the issue--this is my first 4 stroke so i am a bit lost--the motor runs fine but i never had this much residue behind boat--the residue in the water is there even when motor not running--how can you tell if its oil or gas--thanx guys or gals

[pscrabber59]

Did you check your motor out of the water yet? Take a look after you run it and see if there is any leakage of gear oil coming out of your drain-plugs, did you use new seals?
Check your engine oil drain plug.

Check your fuel connections to see if there's a leak

[pscrabber59]

You can tell a gas leak by smell i would think