[Bob Bidonde]

I had this same problem, and it turned-out to be the piston rings were not sealing properly in my rebuilt engine. I used synthetic oil before the rings seated. After changing the motor oil to SAE 10W30 detergent, non-synthetic for a few hundred miles, the oozing stopped and I returned to a synthetic blend 10W30 (Mobil 1).
By the way, a compression check was normal for a freshly rebuilt engine.