What would cause saturated oil to appear from my exhaust port of #2 cylinder. Was driving and engine started missing. I opened the hood and saw oil around exhaust manifold under #2 cylinder. Oil was not burned but was saturating the outside of exhaust manifold in one spot. New rebuild on engine .090 bore with new pistons. Ran fine until now.
Probably a mix of carbon, gas and maybe a bit of oil too. Since you say "new rebuild" I'm thinking that your head gasket needs to be re-torqued, (as they usually do after a short run-in time), and that it's currently blowing out the "oil" that you see on the manifold.
The dark gooey substance is not unusual by itself. You'll see similar leaking past a spark plug with bad threads or a head bolt that has combustion gases leaking by it, (due to a leaking head gasket).
My thought is that the exhaust manifold gasket has a little leak there AND you are running your carb/fuel mixture just a bit too rich.
If you are running over-rich enough that dampness would show at a manifold gasket leak, then you are probably running over-rich enough that you will probably foul the plugs pretty soon too...