Thanks for the replies guys. I'm starting to try my hand at repairs based upon the encouragement of a local friend of mine who posts here-samneric. Saturday I successfully pulled my door apart to fix a fallen lock mechanism, and now I'm trying my hand at simple (!) A/C repair. I'm replacing the o-ring where the High Pressure line joins with the A/C compressor after we detected a leak at that spot.
As far as underhood, it simply states "DH-PR".
I've called the two local Subaru dealers, speaking directly to mechanics, who could only tell me to use PAG.
It sure would be nice to see a documented recommendation somewhere. I'm about to the point where I'm going to start calling random Subaru dealerships all over the U.S. until I get a reply.