Just to clarify that the 2.4DIT does not allow/recommend 5W-40. That was only in the 2.0 DIT. They do still allow the Euro 0w30 though. This is from the JDM WRX manual with the 2.4 DIT.
So I just purchased a new Subaru Outback Onyx XT. I’ll be doing an oil change around 2,500 miles to get all the assembly junk out of the engine. I live in northern IN so hot summers, cold winters. Commute is about 12 miles a day. I’m not brand loyal, and don’t care if I change weights from the 0W-20 the manual recommends.
For our Gen 5 OB, I now use 5w30 instead of 0W20 (and Suabru Japanese manual specifies various viscosity from 20 weight to 40). However, for current Gen, the Japanese manual only indicates 16 - 20 weight oils....YMMV.