wrong oil in outboard engine petrol?

My 25Lt outboard engine fuel tank was half empty, I filled it up but added the wrong oil to the can,I put in oil for air cooled engined instead of out board engine oil.
I have read on the internet that you should not use the oil for air cooled engines in outboard engines because of damage but as it was only a half empty
Do I
1. Not use this petrol at all
2. Add more of the correct oil to the mixure.
3. Store the petrol and use fresh fuel with the correct
oil and possable add a little of the store fuel to the
can a little at a time over a period of time to get
rid of it.
I would be grateful for you advice.

John drake
July 2008