Originally Posted by marine24
Don't feel too bad, everyone makes mistakes. At least this is a relatively easy one to fix. I had a guy come into a parts store I was working in and bought head gasket repair and poured it into his gas tank. We tried to reason with him that it went in the oil, but he refused to listen and drove off. He came back in about 30 minutes later saying his car wouldn't start; go figure...
I know someone who put radiator Stop-Leak in their gas tank. And another person who put red Loc-Tight on their spark plugs. Sigh.
OP, not the end of the world. Get a wet-dry vac or a turkey baster and suck everything out of the reservoir. Don't drain/flush the coolant or start the motor until you've done this.