Coolant basics – our hot tips
Water mixed with ethylene glycol antifreeze/coolant is the most common coolant in use today.
Pure water was used in the past, but this led to oxidation and corrosion of metal parts in the cooling system, and rust particles blocking coolant passages. Water also freezes at 32˚F (0˚C) when not under pressure, such as when the engine is not running, which causes it to expand and possibly damage the engine.
Alcohol mixed with water and rust inhibitors was another early coolant. The alcohol lowered the freezing point of the mixture, but also caused a lower boiling point than water alone. Alcohol also tended to escape from the cooling system more easily than water. For this reason alcohol/water mixtures were generally used only in colder weather conditions.
Although ethylene glycol does not transfer heat as well as water, its freezing point is much lower and its boiling is much higher. Most vehicles need an antifreeze/coolant and water mixture to generate high enough temperatures to activate the high temperature engine warning light. With only water in the system, damage to the engine could occur if it was all boiled away, never having reached a temperature to activate the warning light.
In addition to ethylene glycol, antifreeze/coolant also contains corrosion inhibitors, rust preventatives and water pump lubricants. It may also contain small particles to plug minor leaks in the system. A 50:50 mixture of ethylene glycol antifreeze/coolant and water will protect against freezing to about -30˚F (-34˚C). The maximum freezing protection is a mixture of 68% ethylene glycol antifreeze/coolant and 32% water, which protects to -90˚F (-62˚C). Any higher concentrations of antifreeze/coolant will actually raise the freezing point, with 100% antifreeze/ coolant freezing at about 0˚F.
Antifreeze/coolant also protects against boiling, with a 50:50 mixture raising the boiling point of water from 248˚F (120˚C) at 14 psi, to 263˚F (128˚C). This 15˚F of extra protection will generally prevent boiling after shutdown in normal operation. Most manufacturers recommend a 50:50 mixture, not only for the freezing and boiling protection offered, but because this concentration also provides the needed corrosion protection.
ENGINE COOLANT COMPONENTS
The components of engine coolants are the following:
- Water
- Ethylene or Propylene Glycol
- Corrosion Inhibitors
- Hard Water Stabilizers
- Coolant Inhibitor Stabilizers
- Antifoamants
- Dyes
COOLANT TYPES
Long Life Coolants
- Orange in color.
- Carboxylate based inhibitor (organic acid)
- Ethylene glycol based
These are hybrid coolants and contain conventional and organic acid inhibitors.
Asian Coolants
- Typically red in color.
- Coolant technology based on amines. Potential problems occur when amine based coolant (Asian) and nitrite based coolant is mixed. A nitrosamine (carcinogen) can form.
- Toyota still uses red amine based coolants Phosphates are also used.
- Borates and silicates are not acceptable in Asian coolants.
- Ethylene glycol based.
European Coolants
- Can be green, blue or amber in color.
- Amines and phosphates are not used (banned) in Europe.
- Nitrites are used, but the trend is to eliminate them. Borates are not accepted by Peugeot.
- Silicates are still used to protect high temperature aluminum.
- Ethylene or propylene glycol based.
COOLANT CONTAMINANTS
Degradation Acids
Degradation acids are formed from coolant degrading through the stress from heat and pressure, plus the deterioration of coolant inhibitors. Degradation acids lower the Reserve Alkalinity (RA) of engine coolant. The Reserve Alkalinity of an engine coolant is the ability of the coolant to neutralize degradation acids before dramatically affecting a coolant’s pH. New engine coolants typically have RA values of >9.5.
Heavy metals
Heavy metals are generated in engine coolants as the inhibitor package breaks down, the RA and pH decrease, and the used coolant begins to attack metal components of the cooling system. Common metals are lead, copper, brass, aluminum, iron, steel, magnesium, and zinc.
Note: While the used coolant is attacking the metal components in the cooling system, it is also attacking the rubber components (i.e., hoses, gaskets, seals).
Depleted inhibitors
A new or recycled coolant contains a complex mixture of chemicals to prevent coolant degradation and provide protection of all components of the cooling system.
The coolants are often referred to as “Fully Formulated” or “Balanced”. As the inhibitors deplete, the formulation loses its balance, and chemicals that once protected certain metals can now attack other metals. Solder bloom is a common result of inhibitor depletion.
Water Contaminants
Water (typically tap water), when added to engine coolants, introduces another group of contaminants to a cooling system. Contaminants such as chlorides and sulfates can actually attack non-ferrous metals (copper and brass) in the cooling system.
Hard water will promote scale deposits and can cause silicates to fall out of solution, producing a “gel” that can clog passageways in the radiator and heater core.
Electrolysis
Though electrolysis is not a fluid contaminant, it is potentially the most damaging because the process cannot be seen. Electrolysis occurs when coolant and dissimilar metals such as copper, brass, aluminum, or cast iron, react electrically.
This generates electrical current in the cooling system, causing a strongly charged metal such as aluminum to be eaten or corroded away. Even though this electrical corrosion process may be taking place, the color of the coolant may still appear normal.
The problem with servicing coolant systems
Car manufacturers require scheduled engine coolant changes to maintain their warranty coverage. They also recommend periodic changes to maintain the system in optimum condition after the warranty period has expired.
Just like transmission fluid and engine oil, engine coolant deteriorates over time, forming damaging scale, deposits and acidic byproducts. These contaminants are difficult to remove when much of the old fluid remains in the cooling system. Engine blocks, heater cores, hoses and water pumps are not typically drained during a traditional coolant system drain and refill.
Sometimes up to 60 percent of the old contaminated coolant can be left in the system after a traditional service.
Traditional engine coolant drain and fill services can also be messy with a high likelihood of spilling potentially hazardous waste onto the shop floor, creating an unnecessary health and safety issue.
But most importantly the introduction of extended life coolant in many vehicles means that service centres must keep it segregated from conventional coolants, otherwise cross contamination can occur. Adding conventional coolant to extended life coolant will eliminate any benefits.
WHY YOU SHOULD USE WYNN'S POWERFLUSH
Unlike traditional drain and fill methods, the Wynn’s Powerflush machines exchange virtually 100% of the old coolant. In addition, the use of Wynn’s Radiator Flush removes rust, scale and other deposits from the cooling system, which could ultimately restrict coolant flow, leading to overheating and possible coolant leaks. The use of Wynn’s Radiator Sealant with the new coolant, replaces factory sealant lost with coolant replacement and helps prevent minor leaks and foaming, and helps lubricate water pump seals.
The orange chassis Powerflush machine services vehicles filled with extended-life coolant. This eliminates the potential of coolant cross contamination with conventional coolants. Wynn’s service is recommended for all cooling systems and is compatible with all types of engine coolant.
