Oil blowing out of exhaust manifold

First, I rebuilt the engine about two years ago. It smoked a little when I started it up. When engine warmed up it quit. Every time I let it sit overnight it would smoke again. Then I put a can of Seafoam in it and it made it worse. I replaced the head (for a second time) and replaced all gaskets. Its still smoking and oil is coming out the exhaust manifold.