Some people post with such fervor that most will assume they know what they're talking about. Remember that the interwebs is full of good and bad advice. With a little bit of research, you'll figure out in time which is good and which is bs.
IMO, the quality of an oil and its suitability for these engines is based more on the oil's properties, not solely on the viscosity. In other words, viscosity breakdown could be an issue, if it actually occurs. For synthetic (both boutique group IV/V oil and OTC group III+/IV) oils, the risk of viscosity breakdown to the point of risking damage or excessive wear is minimal, IMO (i.e., Amsoil HDD 5W-30 will provide more protection, longer than non-synthetic Napa-brand 10W-40.)
It's true that the Napa stuff will start with and probably end its life at a higher viscosity than the Amsoil, but that doesn't mean that it will perform or protect your engine any better or for longer. Speaking of longer, a higher quality oil will not only have a better base stock, which will resist breaking down in the short and long term better than a cheaper mineral-base oil, but may also have a better additive package. The use of higher quality base stocks allows synthetics to contain less additives used to achieve and maintain viscosity, and more additives used to minimize wear and keep things clean.
There is a trade off when you choose an oil, however. Just because a synthetic is thusly labeled does not mean it's equivalent to every other synthetic. As I mentioned, there are highly refined mineral oils that make up the bottom rung of "synthetic" oils like Mobil 1 0W-40 or Rotella T6 5W-40 (which may or may not contain some portion of actual synthetic oil or additives mixed in,) and then there are actual synthetically derived oils like Amsoil, Redline, Motul, etc. As such, it's safe to say that an oil like Amsoil or Motul, under certain circumstances, will be able to pretty easily go to 7,500 miles, while running a "lesser" oil like Mobil 1 OW-40 may not fair as well. While it may be fine, I most certainly would not run Mobil 1 OW-40 out to 7,500 miles unless my commute was mostly highway or I had a Used Oil Analysis (UOA) to back up that long of an interval.
As you can see, there are many choices, and while many will point you toward or away from certain oils, none of those recommendations is necessarily the right choice for you. The only advice that I can offer is that you should most certainly stay away from what called Resource Conserving oils, which are usually thinner and less shear-resistant under high temperature conditions. As the name implies, they're designed for max fuel economy, not necessarily max engine protection, and while the level of protection afforded to most motorists is more than adequate, the same may not be true for your turbo-charged Subie.