Do I have to put coolant in my car's radiator? Will water do? I had the impression that the so-called coolants are anti-freezes, which are not applicable to a hot and humid place like Singapore.

The coolant used in a car's cooling circuit has the ability to raise the boiling point of water as well as lower the freezing point.

In fact, a 50 per cent mixture of coolant - usually ethylene glycol-based - with water will raise boiling point to 108 deg C and lower freezing point to as low as minus 39 deg C.

The latter is, of course, not relevant to Singapore's climate.

But having an appropriate amount of coolant in the car's cooling system is necessary for a couple of other reasons (besides raising the boiling point by 8 degrees).

Radiator coolant contains a rust-inhibitor. This is crucial, since water can cause rust.

If you do not have enough coolant in the radiator, rust will form over time. And you can see this when the radiator water turns rusty orange.

In addition, the coolant has the property to provide lubrication to the water pump shaft, hence reducing wear.

Having a coolant mixture instead of plain water in your car's radiator is therefore important and necessary.