'74 GTV 2000 oil pressure drop

[Jeff Matson <jsm8@xxxxxxxxxxx>]

     Had a bit of a scare recently while driving my '74 GTV 2000 on the
highway.  I noticed that the oil pressure gauge had dropped from its usual
50 to around 10.  I'd like to know what the cause of this problem might be,
and maybe what sort of repairs I'm looking at.
     After letting the car cool down completely, it restarts at the usual
50 on the gauge, so I'm inclined to think there's a physical problem,
rather than a sender unit fault.  (But if restarted hot, the pressure stays
low.)  The oil pressure warning light doesn't come on ever, and the coolant
temp never rises above its usual 170 on the gauge.  My first guess is that
the oil is getting heated more than usual and causing the trouble.  When I
remove the olio filler cap there's a pretty good flow of air coming out;
this leads me to think that maybe I've got piston blow-by and the hot gases
are causing the oil heat, or something like that.  Things have otherwise
been in good shape, and the engine (original) only has 65,000 miles on it.
I hadn't noticed this problem before, though I've been driving it just
around school recently with no long trips.
     Am I on the right track, or should I look elsewhere?  Also, given
these symptoms, is this something that can be driven gently to my Alfa
mechanic (25 min away) or should I tow it?  I don't want to make the job
any bigger that it already is...  

     Jeff Matson
     jsm8@domain.elided

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