Dan,

Your oil on the belly and excessive use problem sounds like my original
Performance Engine.  I finally installed a pressure gauge in the crankcase
breather.  My engine would show zero pressure on the ground regardless of
power setting.  On the takeoff roll still zero.  At about 120 knots it would
jump to 5" and stay there until power was reduced.  When MP was slowly
reduced to about 18" the pressure in the crankcase vent line climbed to over
30".  That was when all the oil was being blown out the breather.  The prop
was unloaded just enough to allow the worn rings to flutter up and down in
the ring lands and allow combustion pressure into the crankcase.   The fix in my case was to replace the Performance Engine forged aluminum
pistons with ECI Iron/Aluminum (like the stock Continental pistons).  With
about 300 hours on the ECI pistons and rings, I get over 10 hours to a quart
and the belly is clean.  I would give Allen Barrett at Barrett Precision Engines a call about the
loss of oil pressure and the oil problem.  You could have a safety of flight
issue.

Steve Colwell  Legacy IO-550