Frequently asked questions / Antifreeze

What is antifreeze?

Antifreeze is a fluid that provides an effective heat exchange in internal combustion engines with water cooling.

Which is the fluid with the best cooling properties?

Water possesses the best ability for effective cooling. It has a high specific thermal capacity, i.e. it absorbs a large amount of heat in the smallest possible volume.

Is it possible to use plain water as a coolant?

No, it is not!

What are the most common damages occurring in a car due to poor quality coolants?

Studies from the late ‘90s show that, in average, 7 of 10 vehicles contain rust and scale. Over 60% of water pumps fail due to problems with the seals and gaskets. Over 20% of the engines fail due to problems with the cooling system. Scale builds up, and only 0.6mm of it can reduce heat loss by 40%.

What are the key functions of antifreeze?

Antifreeze is a fluid designed to:

-       provide effective heat exchange

-       protect metal surfaces from corrosion

-       prevent freezing

-       be compatible with plastic parts and rubber seals

-       have low-foaming property

-       be  chemically stable both at low and high temperatures

What metal surfaces used in the automotive industry should be protected against corrosion with antifreeze?

The basic metals to be protected are: iron, steel and cast iron, aluminium alloys in the form of castings or stamped pieces, copper and brass, as well as lead-based solders. The traditional copper or brass radiators are being replaced with aluminium radiators with plastic overflow tanks.

What is the composition of coolants?

Coolants are usually made of ethylene glycol, propylene glycol, glycerine and additives.

What additives are used in different types of antifreeze and what is their purpose?

- Corrosion inhibitors;

- Stabilisers – they prevent the release of inhibitors, for example silicate stabilizers

- Dispersant stabilizers - prevent deposits caused by hard water

- PH buffer substance - maintains the desired pH level

- Anti-foam – control the foaming property

- Colours – used for identification

What is an inhibitor?

The inhibitor is a substance which acts as a process retardant. In antifreeze fluids it is a chemical additive to protect metal surfaces from corrosion.

The most common inhibitors typically used in antifreeze include borates, phosphates, benzoates, nitrites, silicates, etc. Inhibitors should be in sufficient concentration to provide the necessary protection for metals.

What varieties of antifreeze are available in the market?

- Traditional - this is a well-known product containing a larger percentage of mineral additives and up to 10% organic additives. It is appropriate for use in engines manufactured before 1995.

- Organic - this antifreeze is based on organic (mono and di-carboxylic acids) and does not contain silicates or potentially harmful additives such as nitrates, amines and phosphates. This type of coolant meets the enhanced requirements for long-term protection of aluminium and iron alloys in modern automotive applications. The antifreeze has a significantly extended change interval and is suitable for engines manufactured after 1996.

- Hybrid - a coolant formulated on basis of organic (mono- and di-carboxylic acids) and does not contain silicate inhibitors or potentially harmful additives such as nitrates, amines and phosphates;

- Lobrid - This type of coolant does not contain nitrates, amines, or phosphates. The components used for corrosion protection are formulated with organic substances and have a much lower content of silicate additives compared with the Hybrid type antifreeze.

- Propylene Glycol-based antifreeze products are increasingly present in the market. The explanation is that coolants of this type are not toxic which makes them particularly preferable for formulating the so-called “ecological” antifreeze.

Does the colour of antifreeze matter?

Quite often the colour of antifreeze is wrongly associated with its application. Antifreeze can be yellow, green, red, violet, blue, or even pink. It is important to note that the colour is not determinative of the quality parameters!!! (Different formulations may come in the same colour or vice-versa). Yet, the colour can be a guarantee indicator.

What antifreeze should I use to top up?

Each ethylene glycol - based antifreeze is miscible with equivalent grades of other brands. When mixing Long-life antifreeze with a coolant of lower performance level, the troubles arise from the fact that components may occur in the newly formed mixture that are not safe for the cooling system. Therefore, if you do not have a product at hand that is recommendable for your car, top up with water and have the fluid level measured before the winter season. Then, if necessary, add the proper product to obtain the desired concentration.

Is it necessary to change the antifreeze?

Yes, it is!

What necessitates its change?

The exhaustion of inhibitors due to the interaction with metals or other components in the system. Their insufficient content leads to general and cavitation corrosion. The higher content, on the other hand, is responsible for the formation of sludge, leaking radiators and overheating. High levels of nitrite lead to corrosion of aluminium components, while the increased concentration of solid particles causes early wear of the water pump.

What is the optimum mixing ratio for the cooling system?

40–50 % of antifreeze concentrate maintained throughout the year.

What are the risks of an improper concentration of antifreeze concentrate?

The improper water - ethylene glycol ratio may result in a worsened heat transfer and system overheating. The higher quantity of ethylene glycol (antifreeze concentrate) increases the coolant’s viscosity and reduces its heat removal property. The higher quantity of water carries the risk of freezing which can result in a very serious damage, such as a radiator crack.

How to top up or change the antifreeze? Are there any specifics?

Of course there are. Mix the concentrate with water in a pot beforehand and then add to the system. This is necessary because if adding pure concentrate alone, the time for it to homogenize may not be enough and as a result areas of water may remain in the system which after freezing and volume expansion may cause damage.

Is it possible to top up antifreeze with tap water?

The PRISTA ANTIFREEZE LONG LIFE and HAVOLINE EXTENDED LIFE ANTIFREEZE COOLANT of Техасо have the necessary dispersant stabilizers which prevent scale build-up from hard water. In other words, scale problem will not occur. However, we recommend the use of tap water only in those cases when distilled or softened water is not available.

When and how to check the antifreeze level?

Visually the coolant level can be checked with each lifting of the bonnet. Another way to check is by preventive testing with a refractometer before the winter. In this case the protection from freezing and the checks must be performed at fluid temperature of 20°С, otherwise the readings may be inaccurate.

What is the mileage-based change interval for an antifreeze fluid?

The mileage will depend on the quality and performance requirements a product complies with. Depending on the brand and type of the product, and on the condition of the vehicle, the interval varies from 3 to 5 years with a mileage of 30 000 to 650 000 km. For passenger cars, the maximum mileage is up to 250 000 unless otherwise recommended by the vehicle manufacturer.

G12? What kind of antifreeze is it?

G12 is short for an OEM specification of the VAG Auto Group. „PRISTA ANTIFREEZE LONG LIFE“ and “HAVOLINE EXTENDED LIFE ANTIFREEZE COOLANT” of TEXACO are the two products that meet the TL-VW 774 D, F specifications and are also known as G12 and G12+ types of antifreeze.

Classifications and Specifications. What do these acronyms stand for?

All currently existing standards for antifreeze have set certain parameter rates:

ASTM – American Society for Testing and Materials;

BS – British Standard;

AFNOR – Association française de Normalisation (the French national organization for standardization)

MIL – Military Standard ;

NATO – Military Standard;

SAE J – US Society of Automotive Engineers

БДС – Bulgarian State Standard