So after changing my oil last week I noticed a small leak at the frame oil drain bolt. So tonight I went to see if it was loose and started tightening it. After about 1 and a half turns the head of the bolt plus about 3 threads just sheared right off. Bad news, I was curious if anyone has any experience with this and can give me any insight as to why this would happen. I am planning to drill a hole and use an easy out extractor tomorrow, but didn't know if there were any precautions I should take as I do not want to mess up anything any further. Any help would be greatly appreciated.