should be checked and changed at regular intervals. After prolonged use, antifreeze will
break down and become very corrosive. It can lose its rust preventative properties and the
cooling system can fill rapidly with rust.
inspection of the antifreeze will help determine its condition. Rub your lingers inside
the radiator filler neck. Check for rust, oil (internal engine leak), scale, or
transmission fluid (leaking oil cooler).
Also check to
find out how long the antifreeze has been in service. If contaminated or too old, replace
the antifreeze. If badly rusted, you may need to flush the system. Antifreeze should be
changed when contaminated or when 2 years old. Check the service manual for exact change
strength is a measurement of the concentration of antifreeze compared to water. It
determines the freeze-up protection of the solution.
There are two
devices used to check antifreeze strengththe antifreeze hydrometer and the
antifreeze hydrometer is used to measure the freezing point of the cooling system. A
squeeze and release bulb draws coolant into the tester, and a needle floats to show the
freeze protection point.
the refractometer, you draw coolant into the tester. Then place a few drops of coolant on
the measuring window (surface). Aim the tester at a light and view through the tester
sight. The scale in the refractometer indicates the freeze protection point.
antifreeze strength should be several degrees lower than the lowest possible temperature
for the climate of the area. For example, if the lowest normal temperature for the area is
10° F, the antifreeze should test to -20°F. A 50/50
mixture of antifreeze and water is commonly used to provide protection for most weather
Vehicles, using an aluminum cooling system and engine parts, can be
corroded by some types of antifreeze. Use only antifreeze designed for aluminum
components. Check the vehicles service manual or antifreeze label for details.