What is the normal freezing point of antifreeze?

[ThomasMarie]

Antifreeze normally has freezing points of -15°C, -25°C, -30°C, and -40°C. How to choose antifreeze: The basic indicators of antifreeze are the freezing point and boiling point. In the market, antifreeze comes in several specifications with freezing points of -15°C, -25°C, -30°C, and -40°C. Generally, it is advisable to choose an antifreeze with a freezing point at least 10°C lower than the lowest temperature in your region. Can different antifreeze brands be mixed? It is necessary to use the same brand of antifreeze. Different brands of antifreeze may have varying production formulas. If mixed, multiple additives may react chemically, rendering them ineffective. How to check if antifreeze is low: Observe the antifreeze warning light on the dashboard. If it lights up, it may indicate low antifreeze levels, though it could also be due to excessively high engine temperature. Check the antifreeze reservoir. If the fluid level is below the minimum mark (MIN), do not continue driving and add antifreeze promptly. Check the water level markings on the antifreeze tank. The antifreeze level should normally be between the maximum and minimum marks. If the antifreeze is below the minimum mark, it indicates a deficiency.

[RicardoLynn]

I've been driving for over a decade, and the freezing point of antifreeze really depends on the region. In places like Northeast China where winter temperatures drop below -30°C, you'll need antifreeze rated for -35°C to -45°C. For southern areas where it only goes a few degrees below zero in winter, -25°C antifreeze is perfectly adequate. However, it's important to note that antifreeze loses its protective properties after two or three years of use, at which point its freezing point will also rise. Last time, I tried to save some trouble by just adding water to dilute the old antifreeze, and when a cold wave hit, my radiator almost froze and cracked. Now I always keep a freezing point tester on hand. Before winter comes, I test the antifreeze to make sure it's at least 15°C below the local winter's lowest temperature—that's when I can rest easy.

[TheoLee]

The mechanic at the repair shop told me that the freezing point of antifreeze isn't a fixed value—it mainly depends on the ethylene glycol ratio. When new antifreeze has a 50% concentration, its freezing point is around -35°C. If the concentration drops below 40%, the freezing point may rise to -20°C, causing it to freeze. I've seen many cars on the road with cloudy antifreeze still in use, which is actually very dangerous—impurities can increase the freezing point by over ten degrees. The most reliable method is to test it with a freezing point tester before each winter; that gadget works like a thermometer—just dip it in to get the reading. Northern car owners should pay extra attention—it's safest to choose a specification that's at least 10°C lower than the local historical minimum temperature.

[VonAlivia]

Car maintenance shop owners often remind customers that the freezing point value printed on the antifreeze tank refers to the new product state. In actual use, the high temperature of the engine causes the antifreeze to gradually evaporate, increasing the proportion of water and raising the freezing point. For example, antifreeze labeled -35°C may actually freeze at -20°C after two years of use. During my quarterly inspections, I found that nearly 30% of vehicles with over 50,000 kilometers have antifreeze that does not meet the freezing point standard. A useful tip is to observe the level of the auxiliary tank; if it frequently drops, be wary of abnormal freezing points. Currently, most original factory antifreeze is rated at -37°C, which is sufficient to handle the severe cold in the vast majority of regions in China.