Home Spare Parts and Accessories Car Radiator Fluid: When to Top Up or Replace

Car Radiator Fluid: When to Top Up or Replace


Topping up the radiator fluid level is not always enough, let’s see how to understand if the water-antifreeze mixture needs to be changed

February 17, 2023 – 10:30 am

Add water to the radiator this is what in the jargon is defined as one of the check engine level operations. Check radiator coolant it is essential at any time of the year because the replacement of antifreeze has become less and less frequent among routine maintenance operations. But How to know if the antifreeze needs to be changed? We will explain this in the next paragraphs. color, characteristics and price of antifreeze liquid with some examples of car antifreeze fluids for sale on eBay Here are radiator fluid checks that you can also do yourself.

Update February 17, 2023: New content and links that are more current and useful for readers


Car antifreeze is actually more correctly defined coolant or radiator as a single water-based solution in the radiator protects the engine summer and winter. As we have already seen, the colors of the coolant have a special meaning. With me universal radiator fluids it has become more of an aesthetic factor than a functional one, in fact the color is useful to understand if the antifreeze needs to be changed or not. In the meantime, it should be remembered that the radiator fluid contains important additives which degrade over time:

  • anti corrosion;
  • antiemulsion;
  • defoamer;
  • anti-boil.

The main thing is to compare characteristics of antifreeze recommended by the manufacturer in the user manual, for example the abbreviations G11, G12, G13, etc. To find out if the antifreeze is suitable for your car, you can enter the brand, model and engine in the myGarage eBay virtual garage and you will avoid a bad buy. If necessary, top up as much as possible, do it only when the engine is cold so as not to add too much and not to confuse concentrated antifreeze fluids (more suitable for replacing radiator fluid and when you are not in a hurry) and those already diluted (ready-to-use for quick topping up), the costs and capacities of tanks on sale are also different. For example:

Motul Auto Cool Classic Green Blue Antifreeze Radiator -25° ready to use – eBay;

Motul Concentrated Blue Green Antifreeze Radiator Coolant – eBay;

Motul G13 Pink Purple Ready To Use Antifreeze Coolant – eBay;

Arexons Red Antifreeze Car Motorcycle Radiator Protection Fluid Ready To Use 2L – eBay;

Arexons Rolin Fluid Green Concentrated Radiator Antifreeze Protection Fluid 1 Lt – eBay;

Red Car Radiator Fluid Anti-Corrosion Freeze Protection Concentrate -26 Rhutten Neutron 5L – eBay;


Change radiator fluid at least every 5 years on a traditional car it can only do him good. And if the liquid constantly works at very high or very low ambient temperatures, it must be ensured that it is not too diluted. In the summer, the coolant was boiling at a temperature lower and close to that of water. In winter, for the same effect, it would freeze earlierhaving a freezing point close to zero.


The constant top-ups of water are the main reason for radiator fluid dilution. This occurs in particular when the cooling circuit has leaks and allows microdrops or steam to escape. Even if the level in the coolant reservoir is brought to the maximum, you cannot be sure that the coolant is doing its job properly. A first clue to understand if the coolant is diluted just compare the color of the one in the pan with the broth liquid. It is clear that not everyone has the same coolant to fill up in the garage. Thus, the simplest test for testing the radiator fluid is measuring its quality with a hydrometer similar to those we tested. If the radiator fluid is too diluted, it will be best to have it replaced in the workshop. Here are some examples of antifreeze testers for sale on eBay:

Professional Car Water Coolant Antifreeze Lamp Tester Meter 74080 – eBay;

BGS1820 Auto Coolant Radiator Antifreeze Tester – eBay.


The radiator cooling circuit, as well as that of the lubricating oil, are sealed and, except in special cases, the engine must not consume too much liquid. If the water level in the radiator drops, there may be a leak along the pipes, on the engine radiator, the passenger compartment radiator or at the level of the cylinder head gasket. If the cylinder head gasket is damaged, there are 2 most common cases:

  • the coolant evaporates;
  • radiator fluid mixes with engine oil.

In the worst case you will find that the radiator fluid has oily traces if the problem is recent until the smell (pungent and bothersome) and the appearance (no longer bright and colored, but rusty and cloudy) worsen. In these cases, it will not suffice replace only the coolant but also solve the breakdowns that the radiator fluid has pushed out.

Source : Sicur Auto



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