I've been following this site closely:
Basically, they take an LS1 in a Camaro (irrelevant, it could be any other car really) and break it in, then they switch to Mobil 1 5W-30. This is the same ACEA A5 oil you and I can buy (and yes, I do, I'm running M1 10W-30 now and use 5,000 mi drain intervals).
They run the car as usual, winter/summer/whatever, and take oil samples every 1,000 miles. They then post the analysis data. So far, they've gone 17,000 miles on the Mobil 1 and are doing quite well! Amazing.
The reason I've posted this even though I've mentioned it before is that they might finally change the oil (!) and I don't know if the oil analysis data will continue to be posted on their site. If you're an oil hobbyist, it's a must-see; if you're only interested in a good oil for your WRX, it's definitely worth a visit to the site.
Although the LS1 is normally aspirated, it does produce adequate power considering the large displacement, and owners tend to push their cars. Plus, it has a reputation for burning oil and/or piston slap, so there are definitely parallels to be drawn between the testers and us IMO. Have a look guys!