Changed the coolant. See this thread:
https://bobistheoilguy.com/forums/threads/g13-coolant-in-old-gm.356655/#post-6160416
And as a first stress test - rode up to Boone this morning.
View attachment 105920
An older gentleman left his new Subaru Forester to come over, complement this old truck, and share a couple stories of the 1995 Silverado he had, and how this is his favorite body style of GM trucks. Good times.
As far as cooling ability - idk what got cleaned up, but improvements are there. Before the coolant swap my temps were in the red range on pic below and varied greatly based on speed. Anything over 65MPH caused the temp gauge to sit 1/4"-1/2" towards the Hot zone.
But now, after flush and with new coolant, it sits at 210 mark and doesn't move much. I went 20MPH, 60MPH, and 90MPH, and through it all the gauge was "glued" to 210 mark. Once I started to climb up HWY-421 - it did move a bit. Uphills moved it to hotter side, downhills cooled it off considerably. Like I said - on the highway temp does not fluctuate anymore. But climbing mountains did play with the gauge a little, yet still much tighter range than before. Here is where the new temp range floats in mountains:
Overall pretty happy with results. I guess it may have had a sticky thermostat maybe? And cleaning+flush cleaned it up a bit? Idk... Do plan to replace the thermostat eventually, but should be good for now.
Heading back to Charlotte now, hopefully the ride back is just as trouble free.