NO! It cannot be caused by the leaks you describe! Those leaks are NOT pressure leaks. In order to actually get pressure THAT low you would have to have a MASSIVE pressure leak.
First thing is the lifters..if they do not collapse and sound off you DO have enough oil pressure!!! Somewhere there is a problem other than the pressure..
I am amazed by the mechanical gauge telling you the pressure is low?...
If there IS a failure it would prolly be the pressure release spring in the oil pump.
The description you gave leaves lots of possibilities... But the lifters holding their oil leaves little doubt their IS enough pressure.
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />