Subaru allows for the use of SL oils in 2.5s at least until 2009, according to the OM for our's.
To the OP, I ran GC in the Forester for 20K, including three winters, and it seemed perfectly fine for the engine.
I've since gone to a thinner and cheaper oil, since GC is probably overkill for an NA Subaru.
There are some good UOAs here that show that a thinner oil will hold up perfectly well in an NA 2.5, which brings into question that bit of Subaru lore that they require thicker oil.
Now, the turbos are a whole 'nother matter.