Cold idle with 10W-40 was about the same as with 5W-30: 45 psi or so.
Once up to temp, I have about 20 psi at idle. It climbs steadily through the 2000, 3000, 4000, rpm range, but plateaus at about 44 psi by 4500 and holds there (or maybe even drops slightly) towards 5000.
My understanding is that a 302 should have at least 10 psi per 1000 rpm. If that rule of thumb is true, I'm still not getting enough oil pressure in the higher rpms.
The second diesel treatment came out clean and the 5W-30/marvel was pretty clean too: just slightly brown. At this point, I'm suspecting my pump and/or bearings are simply worn like one would expect from an engine with nearly 200k miles on it that probably wasn't meticulously maintained.
What do you guys think? All this flushing absolutely made an improvement, but it's still not where it should be. Time to commit to 10W-40 and run it as long as it holds together?