Best oil for My Slant 6

I respect and appreciate the knowledge all of you who have probably forgotten more about engines, and more specifically Mopars than I will ever know!!

BUT I direct your attention to the fact that:

Rotella T6 is listed as a "SN" rated oil.. on the back of the bottle
Here is the Rotella advertisement cut and pasted for easy reference:

EDIT: T4 may not be to the same standard, with I have not looked into!

Shell Rotella® T6 Multi-Vehicle Full Synthetic engine oil performs extremely well in diesel and gasoline engines, meeting both API CK-4 and API-SN standards and allowing mixed fleets to consolidate lubricants.