BlueSubie Is that an endwrench article? If so you cannot trust it. It is published by a different part of subaru and they often get stuff wrong.
Originally Posted by CTSSM2011STI
5W-30 synthetic oil is required for optimum engine performance and protection.[/color][/u] Conventional oil may be used if synthetic oil is unavailable.
*: If 5W-30 synthetic oil is not available, 5W-30 or 5W-40 conventional oil may be used if replenishment is needed but should be changed to 5W-30 synthetic oil at the next oil change.
I think you just proved my point that synthetic is not required
There are plenty of great conventional oils, and there are some crap synthetics. Either way if it meets the API ratings they specify and you are within the viscosity range it will work.