What happens if blue and red antifreeze are mixed together?
Antifreeze is a chemical consisting primarily of ethyl glycol. When mixed with water, it lowers the freezing and boiling point of the mixture. Unlike air-cooled engines, those equipped with a water cooling system have a radiator and other elements that help to even out the temperature.
Inside the system, the antifreeze is transferred in a cycle driven by the water pump, from where it obtains the heat of combustion and transfers it to be cooled again. It also provides the hot air for heating the car, through another radiator, and the cycle starts all over again.
The concentrated antifreeze has not been diluted with water, unless the product label clearly specifies it. It contains the chemical elements that allow it to work better at extreme temperatures, but if we only add this antifreeze liquid to the cooling system, due to the hardness of its components, it can generate oxidation.
You should not mix an organic antifreeze with an inorganic or hybrid antifreeze. The base of most organic and inorganic antifreeze is the same, ethylene glycol, but their anti-corrosive components are incompatible. They can even react with each other, nullifying their properties and causing problems in the cooling system.
This is because they are intended to protect different materials from galvanic corrosion. If there are different metals touching each other within the same conductive liquid, the exchange of electrons will create an oxidation that deteriorates them. It is not an absolute rule, but organic antifreezes protect the metals used in modern engines and inorganic antifreezes protect those of older engines.
For example, Motul Organic Pink and Motul Organic Yellow have the same 50% concentration and identical temperature resistance: from -35º to 145º. However, the former is indicated for cars and transport vehicles, while the latter is also valid for motorcycles.
Antifreeze of different brands can be mixed.
So what gives Prestone the confidence to claim “all makes and models”? It contains phosphates, not silicates, so it is safe to use in the cooling system of a Japanese car. It can also be used in any non-Japanese car as long as North American water is used. So to support their claim Prestone simply specifies that their coolant be used in North America! Simple. See:
“Some European automakers are requesting that a phosphate-free antifreeze be used in their vehicles. This issue is related to the extremely high mineral content of water in Europe … in North America we do not have this type of water issue … the phosphate issue is not an issue here in North America. Prestone® antifreeze/coolant is completely safe for use in foreign and domestic vehicles.”
I have not seen this problem with other brands of coolant, or with the new Dexcool formulation, which is red. But it’s the orange stuff they sell in stores. Do not use it under any circumstances.
Red and green antifreeze can be mixed.
Among the usual maintenance tasks is to maintain the coolant level and change it when necessary. If you want to perform such a task it is important that you know a few things about antifreeze.
Thus, its main function is to remove heat from the engine to prevent metal parts from reaching temperatures at which they could melt. In addition to being temperature stable, it must also protect against rust and corrosion, while its viscosity must be low.
It is mainly composed of distilled water and various chemical agents which, in addition to taking care of the various elements of the system, on the one hand increase the boiling point (+120°C instead of the 100°C of water) and, on the other hand, reduce the freezing point, which allows the mixture to freeze at a lower temperature than water.
For this reason, when purchasing the coolant, we must follow the manufacturer’s instructions in the car’s maintenance book, as well as taking into account the temperatures usually reached in our geographical area in winter.