Oil/Gas sheen in water

[nhmtnlaker]

I notice an oil/gas sheen on the water when I shut down my boat. Not sure if related but a little smoky when I start it cold as well. Any ideas where to look for leak, if that is what it is? I didn't find anything yet but will look closer now that I have pulled it out of lake for the season. Boat is:
1987 197 Chapparl bowrider I/O w/ 200 hp Mercuiser Alpha 1

Boat has low hrs for it's age and this is my 3rd season with it

 

[Haut Medoc]

Re: Oil/Gas sheen in water

Drain & pressure test your drive.....
Is the choke operating properly?.....
When was the last tune up?......​