I found one oil pan bolt (M6) on the M117 engine that appears to be stripped out. It would not tighten so I removed the M6 bolt and installed it from the top side to see if any debris would come out. As I tightened the bolt from the topside and while looking up into the hole from under the car with a light, metal debris fell out.

Could a Helicoil clean up the threads? What size Helicoil will I need?