I have a 72 cutlass. I've had it for about 2 years now and when I bought it, there were silver "oldsmobile" valve covers on it. In the trunk, I have the original valve covers. There has been a pretty bad oil leak for a while now and it looks like oil is coming out of the filling tube. I think it may have something to do with the valve covers on the motor now. The original valve covers both have air holes for PCV hoses to aid in breathing.

My question is... Does anyone know exactly why the oil may come out of the filler tube?? Is it because the "custom" valve covers on it doesnt allow the proper air circulation? And would the solution be to put the old valve covers back on?

 

Your best bet is to go back with original & new gaskets for proper crankcase ventilation