That said, if the truck had green coolant in it from the factory and the change to dexcool is made, GM recommends that the coolant still be flushed every 30,000 for the next 2 to 3 flush cycles (60-90,000 miles) then the dexcools full 100,000 mile service life can be followed. This is because if any IAT coolant remains in the systems when the change to dexcool is made, the dexcools corrosion inhibitors begin breaking down sooner. Essentially, it's just a precaution.
Everything I snipped is good information as well, but I wanted to focus on the highlighted section.
Dexcool® coolant is rated for a service life of 5 years
or 150,000 miles, whichever comes first. Unless you're driving the thing commercially, 5 years
almost always comes first.
The older IAT coolants are good for 2 to 3 years or about 30,000 miles.
For GM Vehicles, my personal preference is Prestone Extended Life Antifreeze/Coolant (part number AF2000 possibly followed with some letter[s]). It's an OAT coolant that isn't as finicky as Dexcool®, mixes with almost any other coolant without any serious adverse effects, and has the same 5 year/150,000 mile service life as Dexcool®. It also seems to have good corrosion protection as far as I can tell. It's more than "good enough" even if it's technically "not as good" as Dexcool®.
Peak has a similar "universal long life" coolant that is probably "good enough" and most of the FLAPSs offer a house brand "universal long life" coolant which is probably also "good enough." All of the universal long life coolants seem to offer the same claims for service life and the ability to mix with other coolants without negative reactions.
Another thing, I tend to replace all the hoses (including all the heater hoses and the bypass hose and any other small hoses in the system) on the 2nd or 3rd coolant change (10 to 15 years out), and I tend to just replace the water pump at that point as well (they also have a limited service life, and rarely make it to 20 years without wearing out and failing).
I always replace the pressure cap when I do a coolant change (every 5 years), and on GM engines with the thermostat at the top, front, I replace the thermostat as preventive maintenance at every coolant change as well. The springs fatigue and weaken on the cap and old caps tend to let coolant boil off, resulting in "mysterious coolant loss" which is often misdiagnosed as a more serious problem. Caps are cheap. And if there's any air in the system at all, the thermostat usually gets air exposure and can corrode and get sticky. Again, cheap part, not worth the risk. If you don't change it, at least inspect it and if you see any corrosion at all, replace it.
Final tip, bleed the air out of the block when you fill it. If your thermostat has a "jiggle pin," you might be able to fill without opening a bleed point to let the air out, but it won't hurt to give it an open port to let the air out. On most S10 engines, the coolant temperature sensor is near the highest point on the engine, right by the thermostat outlet and that makes a great bleed point. The heater hose connected to the manifold port is also a good bleed point and if you're changing that hose anyway, just leave it loose at the manifold until you've filled the system to the point where coolant comes out there. Then connect it, tighten it and top up the rest of the way. Same thing if you use the coolant temperature sensor port to bleed the air out. Remove the sensor, fill until coolant starts to flow out that port, reinstall the sensor and top up.