Antifreeze compatibility

Antifreeze compatibility allows the mixing of different coolants. Specifically, different grades, colors and specifications. However, you must fill or mix different coolants in full compliance with the antifreeze compatibility chart.

If you ignore information given there then in the best case the received coolant will not correspond to the norms and will not cope with its tasks (on engine cooling system protection from overheating). In the worst case it will result in corrosion of separate system parts surface, engine oil life decrease for 10...20 %, fuel consumption increase for 5 %, risk of pump replacement and other unpleasant consequences.

Types of antifreeze and their features

To understand if you can mix antifreeze you should understand those physical and chemical processes that accompany this action. As all antifreezes are divided into ethylene glycol and propylene glycol, their compatibility will depend on the type of basis.

However, compatibility will be determined by the standard. For the US, ASTM D 3306, ASTM D 4340: ASTM D 4985 (ethylene glycol-based antifreeze) and SAE J1034 (propylene glycol-based) are often considered international. For England — BS6580:1992 (almost similar to G11 from VW), for Japan — JISK 2234, for France — AFNORNFR 15-601, for Germany — FWHEFTR 443, for Italy — CUNA, for Australia — ONORM.

But ethylene glycol antifreezes have another feature of their own as they are divided into several subspecies. Specifically:

• Traditional (with inorganic corrosion inhibitors). According to Volkswagen specifications are designated as G11. Their international designation is IAT (Inorganic Acid Technology). They are used in cars with older types of engines (mainly those whose parts are made largely of copper or brass). Their service life is 2 to 3 years (less frequently longer). These types of antifreeze are usually green or blue in color. In reality, though, color has no direct bearing on antifreeze properties. Accordingly, you can only partly rely on the color, but do not take it as the ultimate truth.
• Carboxylate (with organic inhibitors). In the specifications of Volkswagen designated VW TL 774-D (G12, G12+). As a rule, they are marked with a bright red dye, less often — lilac-purple (specification VW TL 774-F / G12+, used by this company since 2003). International designation is OAT (Organic Acid Technology). The service life of such coolants is 3...5 years. The peculiarity of carboxylate antifreezes is the fact that they are used in new cars, which are originally designed only for this type of coolant. If you plan to switch to carboxylate antifreeze from an old one (G11), you must necessarily perform the procedure of flushing the cooling system with water first and then with the new antifreeze concentrate. Also all seals and hoses in the system must be changed.
• Hybrid. Their name is explained by the fact that such antifreezes include both salts of carboxylic acids and inorganic salts — usually silicates, nitrites or phosphates. As for color, there is a wide range of options, from yellow or orange to blue and green. The international designation is HOAT (Hybrid Organic Acid Technology) or Hybrid. Although considered worse than carboxylate antifreezes, many manufacturers use them (for example, BMW and Chrysler). In particular, the BMW N600 69.0 specification is much the same as G11. Also for BMW cars, the GS 94000 specification applies. For Opel — Opel-GM 6277M.
• Lobrid (international designation — Lobrid — Low hybrid or SOAT — Silicon enhanced Organic Acid Technology). They contain organic corrosion inhibitors in combination with silicon compounds. They are the most advanced and have the best performance characteristics. In addition, the life of these antifreezes is up to 10 years (which often means the entire life of the car). They meet the specifications of VW TL 774-G / G12++. As for the color, they are usually red, purple or lilac.

Years of different standards by year

However, the most modern and advanced today are antifreezes based on propylene glycol. This alcohol is safer for the environment and humans. It is usually yellow or orange in color (although other options may be available).

Compatibility of antifreeze between each other

Can you mix new antifreeze with your old, which is poured into the cooling system is easiest to navigate by the specification Volkswagen.However, technically more competent to use and mix those antifreezes that meet the tolerances of the manufacturer of your car (not those that were adopted by Volkswagen). The difficulty here is, first of all, to find those requirements directly. And secondly, not all anti-freeze packaging indicates that it supports a certain specification

The most important rule to remember is that adding (mixing) antifreeze, not only of the same class, but also produced by the same manufacturer (trade mark) is permitted. It is conditioned by the fact that in spite of the similarity of chemical elements different companies use different technologies, processes and additives. Therefore, when mixing them, chemical reactions may occur, the result of which will be neutralization of the protective properties of the resulting coolant.

Antifreeze to refill	Antifreeze in the cooling system
	G11	G12	G12+	G12++	G13
G11
G12
G12+
G12++
G13

Pay attention to the fact that some antifreeze classes are in principle incompatible with each other! So, for example, it is impossible to mix coolant of G11 and G12 classes. At the same time, mixing of G11 and G12+, as well as G12++ and G13 is permitted. It should be added here that mixing antifreeze of different classes is only allowed for a short time.

Antifreeze Compatibility by Color

Before answering the question of whether you can mix different colors of antifreeze, you need to go back to the definitions of what are the classes of antifreeze. Let us remind you that there are no clear rules about what color this or that liquid should be. Moreover, some manufacturers have their own differentiation in this respect.

But historically, most antifreezes of G11 class are green (blue), G12, G12+ and G12++ are red (pink), and G13 is yellow (orange).

Therefore, the next actions should consist of two steps. First you must make sure that the color of the antifreeze corresponds to the class described above. Otherwise you need to be guided by the information given in the previous section. If the colors match, then the reasoning should be the same. That is, you cannot mix green (G11) with red (G12).

Antifreeze compatibility

For other combinations, you can safely mix (green with yellow and red with yellow, that is, G11 with G13 and G12 with G13, respectively). However, there is a nuance here, because antifreeze of classes G12+ and G12++ also have red (pink color), but they can also be mixed with G11 with G13.

How to check antifreeze compatibility

How to check antifreeze compatibility

To check the compatibility of different types of antifreeze is not difficult at all, even at home or in the garage. The method described below will not give a 100% guarantee, but visually you can still assess how one coolant can work in one mixture with the other.

Specifically, the way to check is to take a sample of the fluid that is currently in the vehicle's cooling system and mix it with the one you plan to refill. You can take a sample with a syringe or use the antifreeze drain hole.

Once you have a bottle with tested fluid in it, add about the same amount of antifreeze that you plan to add to the system and wait a few minutes (about 5...10 minutes). If there is no violent chemical reaction during mixing, there is no foam on the surface of the mixture, and no sediment at the bottom, it means that antifreezes do not conflict. Otherwise (if at least one of the listed conditions appeared) you should give up the idea of using the above antifreeze as a refill fluid. To make the test reliable, you can heat the mixture up to 80-90 degrees.

General recommendations for topping up the antifreeze

At last we give some general facts concerning refill, which will be useful for every motorist.

1. If you use copper or brass radiator with cast-iron engine blocks in your car, in its cooling system must be filled with simple antifreeze G11 (usually green or blue, but you need to specify on the packaging).
2. If the radiator and other elements of a car engine cooling system are made of aluminum and its alloys (and most modern cars, especially foreign cars, are such), it is necessary to use more advanced antifreezes of G12 or G12+ class as «coolant». Usually they are pink or orange. For the newest cars, especially sports and executive class cars, you can use lobrid antifreezes of G12++ or G13 types (this information should be specified in technical documentation or in the manual).
3. In case you don't know what coolant fluid you have at the moment in the system, and its level is very low, you may add there either up to 200 ml of distilled water or antifreeze of G12+ brand. Liquids of this type are compatible with all the above-mentioned coolants.
4. Generally speaking, you may mix any antifreeze fluids except for domestic «Tosol» with any coolant for a short period of time. Also you may not mix G11 and G12 antifreezes. Their compositions differ, that is why the arisen chemical reactions at mixing can not only neutralize protective actions of the mentioned coolants, but also destroy rubber sealing and/or hoses in the system. And remember, do not drive for a long time with a mixture of different antifreeze! At the earliest opportunity, flush the cooling system and refill with the antifreeze recommended by the manufacturer of your vehicle.
5. The ideal way to refill (mix) antifreeze is to use the same canister (bottle). That is you buy a big capacity bottle and fill in only a part of it (as much as the system needs). And the rest of the liquid you either store in the garage or take with you in the trunk. This way you will never make a mistake with choosing antifreeze for refilling. However, when the canister runs out, it is recommended to flush the engine cooling system before using new antifreeze.

Following these simple rules will allow you to keep your engine cooling system in working order for a long time. Also remember that if the antifreeze does not perform its functions, it is fraught with an increase in fuel consumption, reduction of engine oil life, the risk of corrosion on the inner surfaces of the cooling system parts, up to the destruction.

FAQ:

• Are all antifreeze compatible?

  Most antifreeze fluids are compatible. The antifreeze can have the same approvals and the same class, or you can use the fluid of another class. But there are several exceptions.

• What coolant should not be mixed?

  Most manufacturers don't recommend mixing antifreeze fluids G11 and G12, they are incompatible.

• Can you mix antifreeze coolant brands?

  You can, but if brands are different, it's recommended to use the same type of fluid.

• Does it matter which antifreeze coolant I use?

  The only rule you can follow — use the type of coolant which is recommended by the manufacturer of your car.