So here's what I'm hearing. There is the school of thought to stick with OEM. A very safe strategy, and a school I subscribed to until recently, at least for coolant, especially as I've learned more over time.
A given regardless of what strategy one chooses is do not mix different formulation types.
Of the coolant types that are of interest to me are the Asian super long life coolants, almost all being virtually the same formulation except for dyes and minor insignificant differences. There is the VW/Pentosin G13/G12 family of coolants, from what I gather, sharing similarities to other European formulas. And there is Dexcool and all of its clones.
All three of these groupings have similarities, but enough differences I would not want to mix them together.
Aftermarket consumer targeted are G05 and PGL. Many extoll their virtues.
Then we have the commercial fleet targeted coolants with near lifetime fill applications for me, such as Peak Final Charge or Rotella ELC.
My understanding of cooling systems are, while there are certainly some design differences, and plastics, rubbers, etc can be different, the systems really are mostly the same in principle overall, and the aluminum alloys shouldn't differ that markedly to warrant different formulas. It seems the OEM strategies for formulas are based on what is proprietary to them, almost reflecting the pride of the respective engineers, compounded by the end user realities in their home markets, which they extrapolate globally.
My thoughts are, my van is due for a second timing belt change this summer. This means I should probably consider replacement of the OE Denso water pump, and as the second fill of coolant is getting up there in age, that is the perfect time to replace it.
First change was a straight drain and fill with Toyota SLL per manufacturer's recommendation. This change, I want it flushed completely regardless of what goes in there.
This could be the first of my vehicles to migrate to a coolant I can eventually use across the board. I am leaning heavily into doing homework to pick out a commercial ELC.
I have some Dexcool on hand to top off the truck, if it needs it, as I believe I have a ways to go on that coolant. And my newest vehicle won't need a change for a very long time, so I will get G13 for top up if required.
I tend to keep vehicles for a very long time, so I think migrating to one of these super extremely long life coolants over time makes sense - likely the last fill I will do ever for each of the vehicles, saving me time. But also at some point, I will be rationalized down to one coolant across the board.
I know I can never get there with oil, though the least picky of the three will inevitably get some leftover oil from the other 2, and though likely possible to do so on these three with ATF, I have no desire to stray from the OE specs of TES-295, T-IV or WS for the respective vehicles. Coolant in my mind, is entirely different.