45 Cetane, if you can get it, Fill up in the morning ( cooler fuel )
you get more energy (volume ) than warmer fuel.
( Florida Diesel is C**P , 40 cetane & HOT )
When you find a " Good" Fuel stop, one that gets good mileage,
Plan your stops there. ( Wilco , exit 205 I81 is my best fuel stop)
Turn off A/C, ( Only use defrost when needed ( A/C))
" 4x4 /NO CAD " consider manual Hub Conversion.
And of course , Light foot
And Lastly, I have not seen any measurable increase in Fuel Mileage with Cetane adders. .