Its the one on the side of the enigne where the tube is held in place.

 

Not unless it's broken away from the dipstick tube, even then it would have a hard time to leak alot. If you've replaced the disptick tube, it may be that there is too much play in the bottom of the tube that goes into the block if you have sanded it or clearanced it in any way.

-Shannon

 

Pretty sure that the hole for that bolt is a blind hole. No way it could leak.