The turbo oil line screen could also be clogged. Some of had luck by simply doing an oil change. Go with Rotella T6 5W-40 or one of the Mobil1 High Mileage
oils (10W-30/10W-40) and do a short 1k mile interval. Subaru actually has a TSB that calls for using a Subaru branded flush (I believe it's the kerosene type flush) and I've heard cases of that working as well. http://www.scoobymods.com/showthread...ine-13825.html
Do you actually hear a tapping sound when the engine is running? Some actually get a tapping sound when the screens are clogged so it's probably a good sign if you don't hear any tapping.