If it was not for bad luck I would have none at all!

How much of the grey sludge is there, really? I've seen a ton of people see a bit of condensation on the oil cap and freak. Have you looked down inside the valve cover and on the dipstick to confirm that the oil is all sludged up like that? If the oil on the dipstick looks good, you probably don't actually have water in the oil.

How does it sound at idle? All clattery? I agree that the first thing you should do is use a mechanical gauge to test the pressure.

The first thing that comes to my mind is a plugged up pickup, or maybe a pressed pickup that has come loose and is sucking air.