The Mobil 1 you want is the European formula. I am pretty sure it is the only M1 that comes in 0w-40 so you probably bought the right stuff
This oil has a very good anti-wear additive package and is full synthetic. Mobil recommends this oil for the 6.4. It has not been tested to the spec because of politics.
They can not void any portion of your warranty for not using their spec oil, as long as you use the correct viscosity and API rating, following the proper intervals.
In no way shape or form must you use the spec'd oil to maintain warranty coverage.