Thanks for all the detail. It's very interesting. I may just go with a 5W-30 synthetic for the first oil change with the Subaru filter. With summer around the corner 5W-30 should work well from what I gather from the sloppy fitting pistons.
If I go with 0W-30 in the future I may just go with Amsoil OE. It's actually cheaper that the Subaru oil at $7.49/qt.
Thanks again for all your contributions.