Subaru says for the 2.5, 0W-20 synthetic every 6000 miles with a new filter.
Use what ever flavor you like, keep all receipts. Or take to your Subaru dealer
for maintenance. Stretching past this may be ok according to the oil manufacturer
but since Subaru is who holds the warranty to your engine, the wise thing to do
is follow their recommendations. After the warranty is expired , do as you see fit!