JH Engine oil pressure issues

[calimus at techography.net (calimus)]

This is a bit OT as it's for the wifes cabby, but hey, it could be a
scirocco if you use your imagination.

Ok, a week or so I posted a similair question, but now I'm in the thick of
things and doen't like what I see.  Both the cars internal gages and a
manual oil pressure gage tell me that after about 15-20min the oil pressure
in the head at idle drops to just below 0.5bar on the vdo gage and on the
manual gage it's so close to 0 I really wouldn't know what to call it.  Now
this is after bumping the oil up to 20w-50 since the PO's had 10w-30 in it
before.  I also flushed the motor twice to make sure all the gunk would be
out of it.

So I figured that it might be the pump (which documentation shows was
replaced in 97' and only 7k miles put on the car since then, but since they
had it done at a shope I was wondering if it had really been done) so I tore
the pump out of our wrecked cabby since i knew it was good, then dropped the
pan on the new cabby and there sites a bright shiny brand new'sh febi oil
pump.  Now I'm conserned since the pump looks like it was just put in
yesterday, could it really be bad?  If figure I'll go ahead and swap the
pumps and see what happens, but I need to know where else I could develope
an oil pressure problem in the head after about 15-20min of good 3bar
pressure.  Now the pressure doesn't fall like a rock, but after about 10min
is starts to drop down as the oil temps reach about 80c.  I'm kinda at a
loss since on cold start pressure is good then falls off.  So if you
guy's/gals can hit me back with things that I can check to try and figure
this out, I would be very gratefull.

Thanks,
William Snyder

88' Scirocco 16v
89' Cabriolet 8v (R.I.P.)
71' Karmann Ghia