Can putting wrong oil in motor cause a leak and overheat

What is your question?

Checked oil and thought it was low so I added 2 quarts of 10w 30 and 2 days later realized it calls for 5w 30 and I checked oil and it is overfilled. The van started to clunk slightly when shifting into 2, and 3 only a couple times. Then I had a major fluid leak and it looked to be oily and smelled like sweet marshmallows. I drove it home like it was and was ok for 10 mins then it started getting hot and then it would cool off a little bit then it got hot and computer said check coolant and overheated. I shut off and looked and there is still coolant in reservoir. So not sure what it is. The oily fluid didn't seem to be radiator fluid. What could it be?