When I was doing my apprenticeship, we had product called Tap-Magic. It was for use on steel and as the name implies, for tapping holes. It didn't take long to figure out it also worked great for drilling and if used for reaming, the holes looked almost polished. It's still around today, but the formula was changed back in the 80's and it's no longer near as good.
Thought that name rang a bell so I went and verified it. I need to ream my 940 cylinder one of these days...
Todd