Product to remove oil stains from concrete for painting?

I'm looking to find some product that can remove oil stains from
concrete so that paint will stick. My shop used to be used by a car
mechanic and now that I build airplanes in it, I'd like to paint the
floor a very light gray or off-white. I don't think that just using
"Gunk" will remove it enough to get the paint to stick. Maybe some sort
of epoxy-like sealer first? Any ideas?


--
Scott
http://corbenflyer.tripod.com/
Building RV-4
Gotta Fly or Gonna Die