Supertech Dexos (API SN, SM) 5w30 is
Mobil1 0w40 is not Dexos approved due to the fact that it meets much higher and stricter limits and requirements such as API SN, SM, SL, SJ, ACEAA3/B3, A3/B4, MB-Approval 229.3, MB-Approval 229.5, VW 502 00/505 00, PORSCHE A40.
Mobil1 0w40 keeps flowing when Supertech Dexos 5w30 turns to honey-like substance in cold temperatures.
And Mobil1 0w40 keeps protecting the engine with increased engine loads, when Supertech Dexos 5w30 gets watery and starts to burn off and plug the piston ringlands with carbon deposits from increased engine loads. (Stop-n-go traffic, 4k+ RPMs, etc.)
In every possible way it is an UPGRADE over any Dexos approved oils, including Supertech Synthetic 5w30. All you gotta do is expand your tunnel vision buddy.