You'll probably hear this all over this place, but...
Based on my personal experience and your previous owner's service indicator-length OCIs with dealer oil, I wouldn't hesitate to do a course of ARX on this vehicle. My M52 has been OCD-maintained since new and I tried ARX for the heck of it. I saw benefits I didn't expect to see given the cleanliness of my engine so...
Castrol GTX 10W40 has some excellent 90s BMW used oil analysis in the used oil analysis forum. I used it in my dad's M62 with ARX last year without incident. In VA you may have no trouble running that starting any time now, or possibly starting in March. You'd probably be done the full ARX cycle before any truly synthetic-worthy weather returned.
After ARX, return to GC or whatever your preference.
Enjoy the car...
Based on my personal experience and your previous owner's service indicator-length OCIs with dealer oil, I wouldn't hesitate to do a course of ARX on this vehicle. My M52 has been OCD-maintained since new and I tried ARX for the heck of it. I saw benefits I didn't expect to see given the cleanliness of my engine so...
Castrol GTX 10W40 has some excellent 90s BMW used oil analysis in the used oil analysis forum. I used it in my dad's M62 with ARX last year without incident. In VA you may have no trouble running that starting any time now, or possibly starting in March. You'd probably be done the full ARX cycle before any truly synthetic-worthy weather returned.
After ARX, return to GC or whatever your preference.
Enjoy the car...