I was about to say OMG another oil thread? But I see you're in Hawaii so I'm not sure what's available there. Motul 300, Mobil 1, Amsoil, and a few others are the most common choices. Any of the name brand f
ull synthetics will work great, nitpicking over one brand being worlds better than the other is like arguing one color is better than another. There are very slight differences but for all intents and purposes, they're all perfectly fine for our engines. 0w20, 5w20, and 5w30 are all within the recommended range, but 0w20 is what the factory recommends and will net the best mileage by a small margin because it's thinner. 5w30 would be good if you see really hot temps frequently, but I don't think that's an issue for you.
Some people have reported issues running Mobil 1 in Subaru's older EJ series engines, although I never did. The FA engine is a completely different animal and shares almost nothing with the EJs besides the flat four layout.
I am also using Mobil 1 (5w20) now in my BRZ and am seeing zero consumption.
So use whatever you want, just make sure it's a name brand full synthetic, check the level occasionally, and drive on.
