I think I'll pass on the so called "Duramax". Here's what my grandson tells me:
General Motors designed their inline six-cylinder 3-liter diesel engine with Opel, a German car company. (GM owned Opel until 2017, where interestingly it was sold to a group that would be bought out by Stellantis in 2021.) Development and engineering took place in Turin, Italy before the engine officially debuted in half-ton Silverados and Sierras in 2019. The 3.0 Duramax, nicknamed “Baby Max”, is manufactured at GM’s Flint Engine Operations plant in Flint, MI, and utilized in GM’s light duty pickups and SUVs.
And this is their replacement for a normal wax thermostat????

temperatures. The primary system replaces a conventional wax-thermostat with an engine coolant control valve.

The assembly is mounted on the driver’s side of the block and made entirely out of plastic, and houses two plastic rotary valves. The rotary valves are a tube with holes in various positions. They are driven by an electric servo motor which aligns those holes with passageways inside the control valve assembly. These two valves are the main coolant valve, which divides and controls coolant flow to the radiator and oil coolers, and the flow control valve that controls coolant flow out of the engine.

The primary cooling system is split into four circuits. Circuit A comprises of the mechanical water pump, and engine head and block. The block and head cooling circuits are in parallel; each has their own individualized cooling passage to localize heating and cooling. Each circuit’s flow is throttled by the flow control valve. The circuit also utilizes three important temperature sensor inputs for the CCV; engine inlet temp, cylinder head temp, and engine outlet temp.

Circuits B and C are supplied with coolant by the main rotary valve and can be turned on or off. Circuit B runs to the transmission and engine oil coolers, which are hooked up in parallel. The engine oil cooler also has an engine oil temperature sensor mounted on it, while the transmission oil temp sensor is internal in the transmission. These oil coolers are mounted on the driver side of their respective components. Circuit C runs to the radiator, with an outlet coolant temp sensor mounted on it. Circuit D always has coolant flow, and supplies coolant to the low pressure EGR cooler on the passenger side of the block, high pressure EGR valve on top by the intake manifold, turbocharger, and heater core. This circuit is also equipped with an electric

water pump after the heater core to help provide extra flow across the heater core and return coolant to the rest of the circuit.