I had seen things over the forums, which id take lightly enough as everyone has there own preference, but i was talking to a senior Subaru mechanic who aswell as working on Subarus for his job monday to friday, also was the head service mechanic for group N and for a short period a wrc car aswell, and he said not to touch Mobil oil.
Ive never used Mobil myself, was always a castrol user and last Subaru used Motul.