Coolant to use
Like said above coolant got flipping complicated. But when I checked it out a few years back I convinced myself the green stuff was a better match with the old style, non aluminum radiators and heater cores.
You will need to change it more often since the corrosion inhibitors don't last as long as the newer stuff.
Furthermore, if the vehicle is very old, and has a sketchy past, I would like to frequently flush at first, so having NO coolant (0% coolant for a few days) helps make it easy, because then you can just drain the 100% distilled water into the parking lot and re-fill, then repeat until it looks normal again (like plain water and not discolored muck).
As a general precaution, Never mix the colors of coolant. Sometimes the bottle will say its ok to mix them though, so just be aware of that.
Also Never use tap water, or drinking water, which contains ions that facilitate electrical continuity which leads to electrolysis and corrosion.
The corrosion inhibitors age, that is the only reason antifreeze needs to be changed out, so running less than a 50% mix means you will need to replace the stuff at more frequent intervals.
We use RMI 25 in all our hotrods, tow vehicles,,,Real inhibitors, keeps the crud from forming.





