Any Secrets for Changing Coolant?

I don't know about the changing portion of your question but my 14 ISX takes orange coolant so double check to make sure its red. Merry Christmas to you also.

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://cumminsengines.com/brochure-download.aspx?brochureid=455&ved=0ahUKEwiu_uq1hKTYAhVG3IMKHdgRCfMQFggtMAA&usg=AOvVaw1sYa6QW4Y3zDEzEWZgxBkh
PDF Cummins maintenance.
If your changing fluid because it's dirty.

I don't know if isx has filter. My n14 does. I would change filter. Maybe flush system also.
Good luck.

 

Lol..hit deer in Wisconsin last July insurance company changed it .

 

I have never done it on a big truck. But I would assume it would be the same as a car engine. Drain it, then refill it with clean water and some radiator flush, then run it for about 20 minutes with the heat wide open. Drain it out, then stick a water hose at full blast in the tank, open the bottom plug or disconnect the bottom hose and let it run with heat wide open again for another 15 minutes or so. Change out the thermostat, replenish with 50/50 and burp the air out, and change the coolant filter while you are at it if applicable.

 

When you drain it, disconnect/drained from the bottom hose. Let it gush out.

 

If you have coolant dirty at this mileage you have bigger problem.
Dirty coolant could be from
1. Exhaust gases contamination - leaking head gasket/ cracks in head or engine block or EGR cooler
2. Oil in coolant contamination - leaking oil cooler.
3 Fuel in coolant contamination - Leaking fuel/water separator.
NADA or some other stores have coolant test kits to check what is in coolant.
Cooling system pressure test overnight will tell you where is leaks.
And yes, Cummins ISX has coolant filter and coolant is red ELC.

 

Very true. Didn’t notice it being a new truck with low miles, OP, listen to Snail Express.

 

Factory fill is Delo ELC coolant.