Delo here currently.
Started using 15w30 SD in my 6.0, I have continued using it in my 6.7 .
But I've run them all, Mobil Delsmack, Valveater Premium Blue, Shell Rosmella, SuperTech, and even Harvest King.
In the conventional 15w40's there really is very little difference in wear rates and overall performance with any of them.