I have a 2007 with the 5.9L and towed FT for 7 yrs
If temps are below 65*F the grid heaters will show in dash
Turn key on and let grid heaters function.....then when symbol disappears start engine.
IF really cold then cycle grid heaters couple times then start engine
That hunk of iron will NOT warm up at idle....not enough fuel/heat happening
So start it and then drive it.
IF you have an exhaust brake use it for faster warm ups
Cool down....
Hard pull then parking let it idle for couple minutes
But most times..by the time you pull off, drive slowly to rest area, to campground etc. it will already have cooled down enough to turn it off.
Idling is NOT good for modern day diesels.....raw fuel washing cylinder walls.
Excessive idling is just not needed.
IF you need to idle use the high idle
High idle feature....truck in park/neutral, parking brake set, cruise control ON
Idle will increase to 1100 rpm.....use ACEL button to increase