I used this to cut holes thru fairly thin, painted metal.  It made the holes like a hot knife going into butter.  No oil needed at all, no overheating, but I had to make sure I did not apply too much pressure, as it can easily cut the hole to the next larger diameter. Remember to do a 'back  cut" from the other side, as when you drill from one side, it tends to push jagged metal out of the way onto the other side. So, light pressure from the back side will get rid of the jaggies and it all will look perfect.