You certainly have to drain the oil, and put the first of what you drain into a quart glass jar and wait for a few days to see if any coolant settles out. And pull the valve covers; if you got coolant in the oil, it will be milky wherever it went.
I all ready have the intake and timing cover off. I will be removing the valve covers next. I will be cleaning and flushing the engine. I will drain the oil, replace the filter, run it and change it again.
