The design of modern engines involves the use of many different materials, including a variety of alloys, solder and aluminium in addition to the familiar cast iron, copper and brass. All these metals require protection against corrosion whenever they come into contact with the engine's coolant.
The antifreeze therefore must not only prevent freezing in winter (and boiling in summer) but it must also provide a high level of corrosion protection.
The latest antifreeze products contain an advanced inhibitor package which helps retain an enhanced level of protection for up to 5 years. They do this by creating an alkaline 'buffer' to counteract corrosive acidity.
Over 70% of new European passenger vehicles are supplied with 'OAT' (organic acid technology) type antifreeze by the manufacturers, in order to provide the required broad spectrum level of protection to all engine and cooling system components.
To comply with the manufacturer's recommendations and provide maximum protection all these vehicles must be refilled or replenished with a suitable manufacturer approved product.