I forgot to mention: when the engine starts cold, the oil pressure shoots up to the top of the gauge (45psi/3bar) even without revving the engine! Why is this? If in fact the oil pump is worn, then why is it that when the engine is cold, it seems to function quite perfectly? Is it simply because the oil is still relatively thicker which is why it exerts more pressure?

Or could it be, say, a wrong oil filter? But then its a perfect fit when I replaced it... weird.

-Don A.