If you have it this far apart, break the glaze on the cylinders and rering it if it doesn't need to be rebored.
I have never added oil for a compression test. Oil will always make compression go higher. What is the point? I guess I've never used that method. Is it to see if all readings go up the same amount and remain consistant? Would it help indicate valve issues over ring failure?
To me, when the engine is at operating temperature with fuel/air in the combustion chamber is a true reading.
What I call a "wet" compression test is pumping the gas pedal once or twice before the compression test reading.
A leak down test would indicate if it is rings or a valve.
Just from what I've read, I would guess at a broken ring, worn distributor bushings, or a valve bent or not seating, or a cam lobe as HotRod L suggests.
