dam already

I had a small block chevy years ago do the same thing with an aluminum intake right were the heat crossover is, a guy told me that it is the heat of the crossover that is drawing the oil thru the porousity of the aluminum. I don't know if it is true or not but it sure didn't do it with the cast iron intake. A leak down test will only tell you if your compression rings are bad not your oil rings. Oil rings are just that they control oil but cannot even new, seal against air pressure. If you are not using a bunch of oil I would say the rings are fine.

Chuck