[Patrick S.]

You can run a 60/40 no problem and benefit from better heat transfer over 50/50.

If you only see hot weather you can change the glycol for some other Coolant/Rust inhibitor.

I run distilled water with water wetter in the XJ.

Not the same green coolant; but this is from a 2009 Ford Escape user manual and matches what I've read:

Your vehicle was factory-filled with a 50/50 engine coolant and water
concentration. If the concentration of coolant falls below 40% or above
60%, the engine parts could become damaged or not work properly. A
50/50 mixture of coolant and water provides the following:
• Freeze protection down to -34°F (-36°C).
• Boiling protection up to 265°F (129°C).
• Protection against rust and other forms of corrosion.
• Proper function of calibrated gauges.