» ServiceSolution antifreeze. A low-tech device, the only variable in testing antifreeze this way is that the hydrometer can be temperature sensitive. A difference of up to 10° F can be seen if the antifreeze being tested is hot or cold. So test the vehicle’s antifreeze as close to the same temperature every time. Another device for testing the antifreeze is more complex. The refractometer actually measures the way light bends as it travels through an object, which in this case is antifreeze. This device is often preferred because it is known to be more accurate — but it can change with temperature just like the hydrometer, so readings could be different depending on the temperature of the antifreeze. One complaint about the hydrometer is that if the coolant being tested has some oil content in it, this can coat the discs inside, causing an incorrect reading. Once the oil has coated the discs, the hydrometer may read other cooling systems wrong. With the refractometer, the glass is wiped clean with each sample and will be more accurate. Keep in mind though, that the refractometer is a bit more expensive. A good hydrometer will cost around $20 — a refractometer can cost
as much as $200. Remind your customer that the cost to maintain their cooling system is cheap compared to the price for you to work on their engine. They may not pay attention to mileage, but money can be a different story. ■
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