newdude

The original TBV was correct at the time the truck was built. It full opened at 194F and that was the normal operating temperature as designed. GM determined due to the mass amount of torque converter failures (which mostly a design of the converter issue rather than the heat but the heat doesn't help as it shortens fluid life) that 194F was "too hot" and lowered it to 158F full open on the new thermostat. You will probably get nowhere with GM on it if the dealer won't help on assistance. This is why its always important to keep records if you are trying for work under warranty or for customer assistance just outside of warranty.

Yes but its only going to show the max gear you are letting it get to. So if you set it to L8 for example, the truck will shift 1 through 8 and locks out 9 and 10. If you manually upshift it, then you'd know what gear its getting into as you as you press the + on the shifter.

After you clear it and the gauge goes back, does it then turn the light on and the gauge goes back to zero? If it does, that's by design per the DTC in the ECM. At the end of the day, its 4 possible culprits. Bad thermostat, bad coolant temp sensor, bad wiring somewhere on the circuit or bad ECM. The first two are the most likely culprits. Action Taken When the DTC Sets DTC P0128 is a Type B DTC. The Engine Coolant Temperature Gauge is inoperative. The A/C is commanded OFF and inoperative. The Cooling Fans are commanded ON. Conditions for Clearing the MIL/DTC DTC P0128 is a Type B DTC. Diagnostic Aids DTC  P0128 occurring causes the Engine Coolant Temperature Gage to default to cold.

Knock on wood I haven't had any of my new trucks consume a drop of oil or no more than a couple ounces to a 1/4 of a quart in an oil change.

Chirps? Like horn chirps?

They don't and they are annoying in the Fords.

Can't speak on towing experience with a 5th wheel camper, but I'm going to say that shopping by GVWR of the trailer is always important. Looks like that model camper is GVWR of 15,000lbs and base curb weight is 11,800lbs. Hitch weight is 2190lbs. Gross combined for your truck should be 24000lbs, towing with 5th or goose 16650lbs. You'd be within the rated limits of your truck. Will it pull it? Yes. Would a diesel maybe have a better time doing it? Probably, if you gotta win a race sure. Would a 2024 6.6 gas with the 10 speed do it better than the 6 speed? Most likely. They are rated to tow more too. Crew gas 4x4 is 18400lbs for 5th/goose.

Likely the culprit. Gotta send it here and there early on to set those rings nice. Ramp up load and RPMs in the first 1500mi, getting to a couple good WOT pulls at that point, then dump the oil and follow whatever regular oil change interval. Rings don't seat good? Oil consumption happens.

Yes to the first no to the second.

Did you check all the other ground straps out? READ HERE - MC-10247361-9999.pdf (nhtsa.gov)

Lower grille shutter is likely failed.

Well... IF you can find one on a lot, it will be on LT, RST, LTZ and High Country trim levels in Chevrolet, SLE and SLT in Denali. If payload is important and you really still want the 3.0, the lower trims will offer better payloads and actually the crew cab 5ft8in typically payload higher as well. Still, its not going to be past 1600lbs by much for a 4x4 3.0 max trailer of any configuration due to engine weight and emissions equipment (heavier exhaust, DEF tank). Also, you won't be able to order one as its no longer available to order with the diesel for the rest of the 2024 model year at the moment. You can order a 3.0 but you won't be able to order with max trailer and the 3.0. I would also add, what are your typical driving needs and towing needs? Small trailer? Massive camper? Short trip daily driving?

It should get "hot" but if its functioning properly, it shouldn't keep climbing. My 2.7 Turbo HO for example while towing yesterday didn't break past 199-205F. When I hooked up it was like 179F. What are your temps empty, say after driving around for 30-60 minutes? Did either dealer actually replace the valve body yet?

Hopefully OP replaced those as you have to pull the intake to do the injectors.

You'd need more than the grille.