Mobil/Advanced fuel economy engine oil SAE 0W-20 1 qt.
I'm also gonna give Eneos a try. I haven't seen anything bad about it on here yet. Mobil 1 is cheap and readily available though...
I bought 6 of the black rokis from ebay, and that should last me quite a while.
If you're bringing the supplies, I'd find a service station you or someone you know trusts already, instead of the dealership. It's just an oil change, you need someone to care about it, they don't necessarily need to have intimate Subaru knowledge.