A 50-50 antifreeze mix is probably best for your car’s cooling system.
It’s a common mistake for do-it-yourselfers. Before the coldest weather, or when they suddenly realize the below-zero stuff is approaching, they drain their radiators. So far so good.
Because they want to be extra nice to a car, they fill the radiator with straight, uncut antifreeze. According to Tom and Ray (Click and Clack, the Tappet Brothers), this is a mistake.
On good authority, they say antifreeze mixed half-and-half with water has a lower freezing point and a higher boiling point.
Antifreeze has another function. It keeps the cooling system from rusting. Change coolant every year or as recommended.
Green-colored antifreeze can be used in any car. Long-life coolants in other colors should be used on recent models. It can damage gaskets in older cars.
If your coolant boils and expands, or freezes, the engine block will be permanently damaged. That brings a very, very expensive repair job.