Antifreeze
Antifreeze as the name suggests is used to prevent coolant from freezing, however it has another property in that it raises the boiling temperature of the coolant. Unfortunately, high concentrations of antifreeze also reduces the coolants primary function of absorbing and transporting heat away from and out of the engines components.
Generally, antifreeze consists almost entirely of ethylene glycol which when used in excessive amounts can also promote corrosion in the cooling system. Ethylene glycol also has a tracking property which can cause leak problems with hose connections, gaskets and welsh plugs on rebuilt engines. As a caution, you should also be aware that ethylene glycol is a toxic substance, which if ingested can be lethal.
When adding antifreeze to a cooling system, a key point to consider is: what is the coldest temperature that the vehicle is going to be exposed to when parked overnight or when in operation? Based on this information, how much antifreeze is required for the protection of the vehicle?