Subaru don't like M1? But, If you find out what they like, please let me know.
I figured out the care and feeding of a EJ253 and FB20 but the FB25 remains a mystery. It seems to want more HTHS than a 20 but not all of a 30. Maybe a candidate for the old 1 quart of 5W30 and balance of the 0W20. I ran EP in a FB25, It seemed to like it: Noisy, but powerful - at least from the passenger seat perspective.
That same engine got the SoA dealer consumption test. Surprisingly and magically, it stopped consuming large amounts of oil. I asked the service writer, what did you put in there? "Just regular bulk oil sir" At the tim,e that was PEAK 0W20 with a Danica Patrick photo on the bottle. The engine clattered on the oil loudly when it got hot, but ran well for trips of 15 miles or less.
Q: How long is you 80% highway trip one way daily? How many miles per year?
I would stick to 10K given my two UOA on the more reliable and quieter FB20 motor
Good luck. - Ken