New issue popped up last year - Newest Diesel oil is CK-4. Per Ford we are not to use CK-4 because there is insufficient lubrication properties (certain parts of the Engine were wearing out to quickly when using CK-4 oil.) See
http://fordauthority.com/2017/03/for...stroke-diesel/ for some explanation.
There is also a list out there that shows the oils that currently meet Fords new specification. Unfortunately I can't find a link to it right now.