Food for thought: 2011+ turbo lof interval is 7,500 mi. Efficiently running stock motor can burn up to 1 qt every 3750 mi. Most A-holes dont check their oil level nearly as often as they should. Proper turbo lubrication is absolutely critical for longevity. What i'm saying is dont just fill it up with gas, never open the hood, beat the crap out of your car, and then run your motor 2 qts low on oil at lof intervals, & then bitch when your "pos subaru" is in the shop. The coking process begins & your turbo WILL fail prematurely. If driven hard & modded, every 2k miles. stock, stick to 3750 tops.
As far as oils: syn 5w-30, 75w-90 & LSD 75/80-90 for rear diff (provided you're not in extreme climates)
As for the similarly described misfire/driveability issues, its not the oil, its likely tight exhaust valves. (but use the rec. oil)