Cooling System Draining and Filling: Notes
With a pressurized cooling system, the coolant temperature in the radiator can be considerably higher than the boiling point of the solution at atmospheric pressure. Removal of the surge tank cap, while the cooling system is hot and under high pressure, causes the solution to boil instantaneously with explosive force. This will cause the solution to spew out over the engine, the fenders, and the person removing the cap. Serious bodily injury may result.
Use only a GM released anti-freeze mixture and ensure a concentration of 50 percent water to 50 percent antifreeze. Antifreeze does not just prevent the cooling system from freezing up, it also protects all the components that are in contact with coolant from rust/limescale deposits. As a result, antifreeze should always be added, even in tropical countries.
In addition to the anti-freeze mixture, water quality also plays an important role. Potable tap water should normally suffice to fulfil this requirement. The quality of regenerated sea water is not suitable.
Damage may also be caused to the engine if unauthorized anti-freeze agent is used.
If radiator, cylinder head or cylinder head seal have been replaced the old coolant must not be re-used.