Good information I will pass it along.Thanks again. I'm not a fan of Auto Zone have had to many problems with the parts from them. Thanks a bunch and have a great day

 

It sounds like a t stat issue to me. I would start with removing the autozone thermostat and install a new Ford part. Autozone parts have a place on old stuff, but on a new diesel truck, no way. My truck gets nothing but OEM parts.

 

Temp guage "all over the place" as you stated in a previous post........tell himto check his coolant level. At least by looking, he could eliminate the possibility.