Mobil 1 sometimes gets a bad rap in the Subaru community because of WRX guys modifying their cars to 400 whp and sticking with GF5 Resource Conserving 5W-30. Then they run Rotella T6 5 and go "oMG! I'm nOT bURniNG oiL! THis Rt6 RocKZ and Mobil 1 sUXoRz!"
Not sure why they don't compare RT6 to M1 Turbo Diesel Truck, but everyone loves to compare apples to oranges.
Run the proper oil grade for your application. Brand is less important unless you're
running some cheap Dollar General no API SL/SM/SN certified junk. 