Heater grid on at 65, and DEF usage too high, any suggestions

[zzman]

Looking for some help from you guys that may know.

The grid heater seems to come on at 65 degrees. Isn't that too warm?
I thought my 5.9 came on around 50 degrees.
Where do I find the temp sensor for this?
I just cleaned the egr system, air horn and heater grids, nasty nasty job.

How much DEF usage is normal? I believe the DEF tank is about 8 gal or so. That seems to last about
2-3 weeks, 2500 to 3000 miles.
Can the flow amount be adjusted?
I got the truck with 63k miles. The DEF fluid lasted about 8000 miles or so then. I took the truck to the dealer with
a loose transmission shifter cable. They said it also had and update to do to it. After that it started using the fluid real
fast. When I mentioned it to the dealer they said it should use about 2 per cent of the amount of diesel used.


Truck is a 2011 C&C. 105k miles. Pulling heavy about half the time.

 

[sag2]

The harder you pull the more DEF you will use.

 

[zzman]

Well I figured that, but it should last as long as an oil change ya think.
My book says at each oil change you should check and re-fill DEF fluid.
Heck I re-fill it 2-3 times between oil changes.

It just don't seem right.