ditto - fully synthetic 10W-50 - ensure it has a JASO or API standard conformance and you should be fine.
My Subaru manual gives quite a range of choice
1.5lt - 2.0lt
10W-30, 10W-40, 10W-50, 5W-30, 0W-20 - with a recommendation of the 0W-20 - however I was advised that would be too light as when the engine is stopped it all runs straight to the sump any residual cooling effect is lost and on start up there is little in the way of lubrication.
2.5lt turbo
10W-30, 10W-40, 10W-50, 5W-30 - with a recommendation for 5W-30