RB Twin Cam Cylinder Head Oil DrainSpool's Oil Drain fitting is designed to help reduce excessive oil build up in the cylinder head of Nissan RB Twin Cam series engines. This is a common problem experienced on the drag strip and occasionally on the street. This kit helps drain the oil back to the sump instead of building up in the head where it often ends up being forced out of tappet cover breathers and catch cans. This Oil Drain fits in the back of the cylinder head (where the OEM