Inner sactum oil galley plug

Duane said
That's not quite how they are drilled. I work for an Oem big three company and sharpen those drills for a living. Step drills are all one drill of two or three different diameters all drilled at one time.
Multiple redrills of the same hole would cost way too much and take too much manufacturing time.
Step drilled holes are a compromise to reduce cost and not to oil your engine better.

Well, I should delete my post because what I said obviously doesn't apply to engine manufacturing. At least not by today's manufacturing procedures. Heck, back when I was operating the automatic screw machines we still used braised carbide tooling. As far as I know the blocks were step drilled the same way back then.