Even if you've changed the PCV valve you need to check ALL of the associated plumbing. The hoses on the engine side(as opposed to the air intake side)can get sludged up or blocked with carbon. I've seen it a number of times.
Also, if the PCV system isn't the trouble, don't just assume that a set of rings will fix it. You need to do a compression check first. If you have enough blow by to push out that much oil then there is a possibility that you have a broken ring or two, a damaged piston, damaged cylinder bore, bent or otherwise damaged valve, etc.. A compression check will tell you more(but not everything). Keep in mind too that a broken ring will scratch up a cylinder wall enough to need boring. It's not just as simple as removing the old and installing the new. In addition, a broken ring will also wear the ring gap of the piston requiring the piston to be replaced.
If you have good, even compression on all cylinders then I would lean towards the PCV or breather side(also check the TB for plugged vaccumm ports). Seeing how it's worse with the synthetic I would normally lean more towards worn rings, but typically you would get a rough running engine if you were blowing out that much oil. That's whats throwing me off here a little.
In the end if it's something major, with the miles you have you're better off replacing the engine with a lower mileage one. They're a dime a dozen and will cost you much less that a rebuild. Especially if you're never done an enginerebuild before(you never mentioned your mechanical ability).
Good luck!
