Silver70,

Your magnum wont have MDS, that started in the Hemi engines around 07, 08 in the cars and some SUVs.

The viscosity code is bogus cause even our owners manuals say to run a heavier oil in extreme heat or climates that get up above the triple digits

I know of more than one person running the heavier oils in their trucks, and LX cars and it really just slows down the MDS activation. It will throw a cam phaser time rationality code.

I finally got back with my Engineer buddy, and we talked on the phone for quite a while. He said to try the 0W40, and the only difference between the 5.7 and the 6.4s MDS is programing. They allow a longer time to see a cam phaser change VS the 5.7 so with that theres a chance I see an issue but Ill try it.