I used to have 5 Subarus in the past, and your consumption is well within the limits.
Subaru manual tells not to worry if you are under one quart for 1000 miles, but it is a little bit… over normal expectations in my view. My last Impreza was around half quart for 5000, my wife’s Outback used to be 1.5 quarts for 5000.
In my experience, Subaru opposite engine design makes it picky on the kind of oil you use.
If you want some theory, you can look for “The Motor Oil Bible” over internet and read through, but let me give you some quick advise which worked well for my Subarus.
Essentially, other than viscosity grade, API grade, etc…, “volatility” (NOACK) is what is quite important for your engine. The test is checking how much oil would evaporate at fixed temperature over fixed time, and it ranges between 6-7 to 15% and even more for different oils brands, making huge difference in that you will see as oil consumption in your opposite engine.
Out of what you can buy at Walmart, I settled on Valvoline SyperSyn 10w30, which had under 10% volatility, and it reduced my Subaru oil consumption immediately (not to mention, engine runs smoother on it). Only some types of Mobile 1 synthetics are as good on volatility (mostly the ones marked for European brands), so Valvoline was kinda “bullet-proof choice” for me.
If you really want to go for the best, look at Amsoil oils: these have very low volatility and work great, but even lazy choice like Valvoline will do better that “noname at chain store”