[sperry]

First, I'm not sure a pressure gauge on the oil cap is going to tell you the crank pressure. It's going to tell you the driver's side head pressure. The only time the heads will see pressure is when the crankcase breather can't keep up with the crank pressure and it pushes oil into the heads. So seeing nothing on that gauge is good, just not a sign that there's no crank pressure.

However, since you just did a rebuild, I'm doubting crank pressure is the culprit, unless those new forged pistons are really loose. Now, you would expect a little extra oil burning w/ the forged pistons, especially on cold startup (are you hearing any piston slap?), but probably not enough to account for your issue.

You might be on the right track regarding the oil weight. I only ran 15w50 when I had a built motor that I was racing in high-temp/high-altitude conditions. I wouldn't run it on the street, I'd stick w/ a good 5w30 recommended by Subaru, like RedLine or Royal Purple. But those oil pressures don't sound unusual. IIRC, that's around the pressures I'm seeing... then again my oil pump is oversized and shimmed... so it might be apples to oranges to compare.

As far as oil in the turbo... what sort of turbo do you have, and how many miles are on it? Is there oil in your intercooler? Do you have a catch can? Is it filling up?

A proper catch can setup on the valve breathers, and second on the PCV/crank breather will immediately tell you if your issue is blow-by/crank pressure, since all the oil you're burning will instead be in the can(s). A check of the I/C for oil will tell you if there's oil getting past the turbo seals... at least on the cold side. If the oil is getting into the exhaust via the hot side of the turbo, I'd expect to see oil smoke.