2009 2.4L has positive crankcase pressure

My son's 2009 Acura TSX 2.4 125,000 miles - same car as Japan Accord - has been losing (probably burning, because no oil spots underneath) oil at 0.5 qt per fillup, maybe a bit less. This car was bought used. We switched to 5W30 synthetic, from 5W20 recommended, which has helped some.
In order:
1. I changed the PCV valve. It was original.
2. I checked the crankcase pressure at the oil fill (should have done this first). It is puffing air out, with no suction. No mistake.
3. I measured vacuum at PCV hose: 15 psi cold, 20 psi as it warmed - this is within spec
4. I checked vacuum at new PCV valve, plugged into PCV hose. There was suction at my finger.
5. I checked that the hole where the PCV valve goes is puffing. It was, indicating no internal blockage somewhere down there.
6. I tried to measure pressure at the dipstick, but apparently < 1psi.

Pretty sure there should be vacuum in the crankcase, as measured at the oil fill. Just like every modern car.

Any ideas?

Thanks,
Dave