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An important choice in the antifreeze industry today is between ethylene glycol (EG) or propylene glycol (PG) as the antifreeze base. For antifreeze formulations each glycol has supporters, although the best choice depends on the intended use. There are several considerations we make when choosing an antifreeze, the most important being performance. In the area of performance there is very little difference in EG and PG. Additives determine most performance criteria so all coolants supplied by a respectable manufacturer will perform well. The one major difference in EG and PG is toxicity. This paper looks at this topic and presents facts for consideration.

Because the most persuasive reason to use PG instead of EG based antifreeze is toxicity, we should discuss a little about toxicity. The first thing to think about is the difference between acute and chronic toxicity. Acute toxicity refers to toxicity that has a short duration. If you survive poisoning with an acute toxin, there are usually no lasting effects. Chronic toxicity on the other hand is something that lasts a long time. When poisoned with a chronic toxin, symptoms may not appear for a long time and they may last indefinitely.

PG differs from EG in both acute and chronic toxicity's. In antifreeze we are most concerned about one time accidental ingestion. Therefore our interest is in acute toxicity. The acute toxicity of PG, especially in humans, is substantially lower than that of EG. Propylene glycol, like alcohol, is not toxic at low levels. In applications where ingestion is a possibility, PG based antifreeze is a prudent choice. To fill this need, Old World Industries markets SIERRA^® and Fleet Charge^® PG antifreeze. SIERRA antifreeze is a PG based automotive coolant. Fleet Charge PG antifreeze is formulated for heavy duty diesel applications.

Another consideration is that all antifreezes pick up heavy metal contamination during service. When contaminated (particularly with lead) any used antifreeze can be considered hazardous. Because of metal contamination many people feel that the toxicity of used antifreeze is the same regardless of glycol. This is where we look at chronic toxicity. PG is not a chronic toxin. EG and heavy metals are chronic toxins. Heavy metals, on the other hand are not acute toxins at the levels found in used antifreeze. For this reason PG based antifreezes, like Fleet Charge PG and SIERRA antifreeze, are much safer for people and pets in case of accidental ingestion even after use.

An area that concerns many people is the impact a used product has on the environment. When discussing this topic we refer to the products biodegradability. The biodegradability of EG and PG are almost identical. Although due to the possibility of heavy metal contamination discussed above it is very important to properly dispose of used coolant, regardless of glycol type.

Glycol is the main ingredient in all antifreezes. With the addition of propylene glycol based products consumers now have a choice in their antifreeze base. For applications where a chance of ingestion exists, the toxicity advantages of PG give it a clear advantage. The choice of antifreeze type depends on what properties the customer desires. Whatever type of properties you desire, Old World Industries has a product to meet your needs.

In many US and Japanese antifreeze formulas, including those produced by Old World Industries, phosphate is added as a corrosion inhibitor. European vehicle manufacturers, however, recommend against the use of phosphate containing antifreeze. The following will examine the different positions on this issue to help judge the pros and cons on phosphate inhibitors.

In the US market, a phosphate inhibitor is included in many formulas to provide several important functions which help reduce automotive cooling system damage. The benefits provided by the phosphate include:

• Protect aluminum engine components by reducing cavitation corrosion during high speed driving.
• Provide for corrosion protection to ferrous metals.
• Act as a buffer to keep the antifreeze mixture alkaline. This prevents acid build-up that will damage or destroy metal engine parts.

European automobile/ truck producers feel that these benefits are achievable with inhibitors other than phosphate. Their main concern with phosphate containing products are the potential for solids drop-out when mixed with hard water. Solids can collect on cooling system walls forming what is known as scale. This concern comes from the fact that European water is much harder than water in the US. Because phosphate "softens" water by forming solids of calcium or magnesium salts that can drop-out of solution, there is potential for cooling system blockage. The phosphate level in most US and Japanese antifreeze formulas do not generate significant solids. Furthermore modern antifreeze formulations are designed to minimize the formation of scale. The small amount of solids formed present no problem for cooling systems or to water pump seals.

For now, Old World Industries believes that phosphate will remain a primary ingredient for cooling system protection. Still, as a good corporate citizen, we continue research on other inhibitor types that will provide the same benefits without phosphates. To show this commitment, Old World Industries is now marketing a heavy-duty antifreeze that incorporates a phosphate free inhibitor package. This new product is called Fleet Charge^® antifreeze. It is a universal formula that passes both heavy-duty and automotive specifications.

In most US and Japanese vehicles, you can use either a phosphate free or phosphate containing antifreeze during the warranty period. However, phosphate containing antifreeze can void European OEM warranties. Old World Industries advises that only recommended antifreeze types be used in these vehicles during the warranty period to ensure complete coverage.

For many years glycol based products have been used for freeze up, boil over and corrosion protection in most vehicle's cooling systems. The majority of antifreezes in use today are based on ethylene glycol (EG), but propylene glycol (PG) products are becoming more common. Regardless of glycol type, antifreeze serves three main functions in a vehicle. These functions are heat transfer, corrosion protection and freeze - boil protection. This paper will discuss each of these topics and explain how to achieve the best results from your antifreeze.

The reason a vehicle requires antifreeze at all is for heat transfer. As an internal combustion engine runs, it generates heat. This heat must be removed. When engines of this type were first designed they utilized water to remove heat. This worked well until winter when the water would freeze and ruin the engine. Originally methanol was added to the water to protect from freezing. The problem with this was that the methanol would boil over in the summer. To solve this problem glycol was added to the water and antifreeze was born.

The question of heat transfer is not as simple as it might seem. The amount of heat a fluid can carry varies greatly from fluid to fluid.

Water is an excellent conductor of heat. Glycols are not as good of heat conductors as water. As the concentration of glycol increases, the heat transfer ability of the mixture decreases. This change in heat transfer is not a problem. During engine and cooling system design the heat transfer ability of the coolant is taken into effect. What is important is not using a fluid that is outside the cooling system design parameters. Modern engines are designed to run with a glycol - water blend between 40% and 60% glycol. Using a coolant outside these limits will cause the engine to run at the wrong temperature. This change sacrifices engine performance and leads to other problems.

The second function of an antifreeze is to protect the metals in a vehicle's cooling system from corrosion. Antifreeze is able to perform this function by the addition of inhibitors. Inhibitor types vary depending on the type of antifreeze. Inhibitors can be of many different forms including organic and inorganic chemicals. One thing that is common with all inhibitors is that they are designed to work in a water solution. The addition of water "activates" the inhibitors, allowing them to protect the metals. For this reason it is important to always mix antifreeze with water in a vehicle's cooling system.

As the name implies the third main function of antifreeze is to protect the cooling system from freezing. The way to achieve maximum freeze protection differs between ethylene and propylene glycol. For ethylene glycol the maximum protection is at 67% ethylene glycol in water. A ethylene glycol solution of this concentration will freeze at -84°F (pure ethylene glycol freezes at 8°F). Propylene glycol does not freeze. It experiences a chemical phenomenon known as supercooling. For this reason there is no freezing point of pure PG. Due to the heat transfer and inhibitor activation reasons discussed above, PG antifreeze should also be maintained between 40% and 70% in water. Boil over protection with both glycols increases with glycol concentration.

As outlined above, antifreeze is an important component in any vehicle. No matter what type of vehicle you drive, maintaining the cooling system according to the manufacturer's recommendation is extremely important. Regardless of antifreeze type, using a solution of antifreeze and water is important to realize the maximum benefits for heat transfer, corrosion and freezing protection.

Standard engine coolants come in three main types, automobile, heavy-duty and universal. The main difference in these coolant types is the level of aluminum corrosion protection they provide. In conventional coolants the addition of silicates provides this protection. An antifreeze designed strictly for automotive use is high in silicate, while a strictly heavy-duty antifreeze contains low silicate. A universal antifreeze meets the needs of both automotive and heavy-duty applications. Universal formulations contain enough silicate to give proper aluminum protection, but keep the silicate level low enough for heavy-duty applications. All antifreezes made by Old World Industries are universal formulations. When used in heavy-duty applications, universal formulations require the addition of supplemental coolant additives (SCAs). SCAs provide the increased protection required for heavy-duty engines. This pamphlet will detail the reasons for needing SCAs in a heavy-duty coolant.

To improve heat transfer and aid in serviceability, many heavy-duty engines incorporate wet sleeve liners. Under the extreme stress of heavy-duty engine operation these liners vibrate. This vibration creates air bubbles that implode against the liners' outer surface. This action, called cavitation, quickly causes pitting that can damage or destroy the wet sleeve liner. Because of this problem, heavy-duty coolants must contain a special nitrite inhibitor, extra defoamer and buffers. These compounds come in a separate SCA. In addition, the SCA introduces a scale inhibitor that prevents the formation of surface deposits in the cooling system. Surface deposits reduce heat transfer and increase boil over potential.

In heavy-duty applications, maintaining a proper maintenance schedule for adding SCAs is equally important as adding the correct initial supplemental additive. Over time, inhibitors deplete and require replacement for proper protection. Generally maintenance SCA additions are every 200 service hours or 15,000 miles (consult individual manufacturers for exact recommendations). The point at which to add a maintenance SCA is determined by test kits made available from the additive suppliers.

In order to reduce the variability associated with SCA levels in both initial fill and top off, Old World Industries introduced Fleet Charge^® Heavy-duty Antifreeze. This is a universal antifreeze pre-charged with an initial supplemental additive package. Fleet Charge antifreeze contains inhibitors and additives to provide the best cavitation corrosion protection and to limit scale build-up. Pre-charging the SCA eliminates many problems associated with over or under adding the initial or service SCAs. Being a universal formula, Fleet Charge antifreeze is suitable for automobiles as well as heavy-duty engines. While Fleet Charge antifreeze eliminates initial SCA charging, the maintenance schedule for SCA addition must still be in place.

Extending the service life of today's vehicles requires proper cooling system maintenance. In heavy-duty vehicles proper maintenance begins with an initial fill of either fully formulated coolant or universal coolant and SCA. After initial fill, a proper maintenance schedule of SCA will ensure a long cooling system life.

Recently the antifreeze market experienced a major advancement, the development of the Extended Life Coolant (ELC). In this type of coolant organic acid salts replace traditional corrosion inhibitors. This new organic acid technology (OAT) represents several major improvements over "conventional" antifreeze technology. As with any new technology, introduction of this new type of antifreeze has caused some confusion. We will explore extended life coolants and go over some of the more common questions asked about this new technology.

In all antifreezes the corrosion inhibitors comprise only a small portion of the total formulation. For this reason the main portion of extended life antifreeze is the same as conventional antifreeze. Conventional antifreezes use inorganic additives to achieve corrosion protection. These inhibitors include silicates, phosphates and borates. Extended Life antifreezes attain corrosion protection by the incorporation of organic acid salts. The main portion of all modern antifreezes is either ethylene or propylene glycol. Because the base of both types of antifreeze is the same, the heat transfer properties, freezing protection and boil over protection do not change when switching between conventional and extended life coolants.

The major performance difference between extended life and conventional antifreeze is the life-span of the product. Conventional antifreeze lasts only two or three years due to depletion of the antifreeze corrosion inhibitors. Because the corrosion inhibitors are different, automobile extended life antifreezes last five years or 150,000 miles. Heavy-duty extended life antifreezes last between 400,000 and 600,000 miles with the use of a one time extender.

Because the chemistry is different in conventional coolant and ELC, it is not advisable to mix the two products. Although the antifreezes are compatible, the inhibitors do not work together. Topping off ELC with conventional coolant dilutes the corrosion inhibitors in the ELC, reducing the usable life of the coolant to that of a conventional antifreeze. Likewise, topping off conventional coolant with ELC does not impart extended life characteristics to the conventional coolant. In an emergency situation, when extended life antifreeze is not available it is advisable to top off with water to hold you over until you get more ELC. When switching between a conventional coolant and an ELC it is a good idea to flush the old coolant from the vehicle before filling with the new coolant. As mentioned above compatibility between the coolant types is not a problem, but the more old coolant left in the system, the less extended life properties the new coolant will have.

Old World Industries manufactures two extended life antifreezes. PEAK Global^® LifeTime™ features a patented, advanced organic acid technoloy for automobiles and light-duty trucks that, with a complete flush and fill, provides a LifeTime protection guarantee - for as long as you own the vehicle. Final Charge^® antifreeze is a red colored heavy-duty antifreeze. Because it is organic acid based, Final Charge antifreeze does not require SCAs when used in heavy-duty applications. Elimination of SCAs greatly reduces the cost and variability associated with heavy-duty cooling system maintenance.

As with any new technology, extended life coolants have caused some confusion. This confusion will wane as consumers become more familiar with this technology. Extended life coolants represent a major advancement over conventional coolant technology. Over the coming years this technology will replace conventional antifreeze and become the industry standard.

Much confusion in the heavy duty antifreeze market surrounds the addition of supplemental coolant additives (SCAs). Heavy duty antifreezes require SCAs to provide cavitation protection. Because SCAs deplete during use, antifreezes require SCA additions many times during the life of the antifreeze. These multiple additions cause a large amount of variance in the level of SCAs found in most cooling systems. This situation is worsened by the fact that most heavy duty cooling systems leak. Leaking systems require "top-off" with fresh antifreeze for proper maintenance. Topping-off with non-SCA charged coolant only adds to the variability of an already variable system. In order to help alleviate this problem Old World Industries has introduced Fleet Charge^® and Fleet Charge/PG^® fully formulated antifreezes. This paper will discuss how using Fleet Charge antifreeze can greatly reduce the variability associated with heavy duty coolants.

When using a conventional antifreeze to initially fill a heavy duty cooling system, addition of a separate SCA provides protection against cavitation. At this point it is fairly easy to determine the level of SCA to add. You know there is no SCA already in the coolant and you know how much coolant you added. From this point forward the situation becomes more complicated. As the vehicle operates, the SCA depletes. With continuing depletion it becomes necessary to add additional SCA. Additionally, most systems leak. In order to maintain the proper freeze protection and coolant level it is necessary to add additional antifreeze. Addition of non-SCA containing antifreeze to make up the volume of antifreeze that has leaked out further reduces the SCA in the antifreeze. Due to these variables the exact time at which to add additional SCA, and the amount of SCA to add, becomes a guessing game.

SCA manufacturers have begun to help with some of these problems. One way to reduce variability is to use coolant filters equipped with multiple doses of SCA. These filters utilize a sacrificial membrane to add SCA to the coolant as needed. The filters sense the SCA depletion and add the correct SCA dosage at the correct time. Although these filters address SCA depletion, they do not solve the problems associated with initial fill and top-off.

For these reasons Old World Industries has introduced Fleet Charge Antifreeze. Fleet Charge antifreeze is a universal formula, low silicate antifreeze that has been pre-charged with a high quality SCA. When initial filling with Fleet Charge antifreeze there is no need to add additional SCA. When topping off a leaking system with Fleet Charge antifreeze, there is no need to compensate for SCA dilution. Use of Fleet Charge antifreeze with a high quality SCA filter greatly reduces the variability often found in heavy duty cooling systems.

Reduced variability is not the only advantage in using Fleet Charge antifreeze. Fleet Charge antifreeze incorporates state of the art corrosion and cavitation inhibitors along with anti-scale additives. For these reasons Fleet Charge antifreeze does not require dilution with DI water (although we always recommend using the highest quality water that is available). Fleet Charge antifreeze is a phosphate free universal formulation that meets all heavy duty and automobile conventional antifreeze specifications. Therefore Fleet Charge antifreeze is also well suited for use in automobiles and light service trucks. This makes it possible for operators of mixed fleets to stock only one antifreeze. Fleet Charge antifreeze stands out from its competitors due to its unsurpassed performance, but it also stands out due to its unique "pink" color.

To be used in demanding heavy duty operations conventional antifreezes require the addition of SCAs. Due to inhibitor depletion and coolant leakage it is difficult to maintain the proper level of SCA. Using Fleet Charge antifreeze and a high quality SCA filter greatly simplifies this situation. To achieve the highest level of performance, always use Fleet Charge or Fleet Charge/PG antifreezes in heavy duty situations.

Propylene glycol (PG) antifreeze comes in two types, motor vehicle and RV. These antifreezes are intended for completely different end uses. This paper will discuss the applications and differences between these antifreezes.

RV antifreeze also known as RV/Marine antifreeze is intended to protect both drinking and waste water systems in recreational vehicles and seasonal homes. It is also used to winterize marine engines which prevents them from bursting while in storage for the winter. Although While -50°F RV/Marine antifreeze will start to freeze at about 10°F it will not burst until -50°F. This is known as burst protection. Burst protection to -50°F is achieved with less than a 35% PG solution. For this reason most RV antifreezes come pre-diluted with as much as 65% water.

RV/Marine antifreeze is also intended to protect drinking water systems from rusting. Drinking water systems are composed mainly of steel piping. Because of the contact with drinking water pipes, a non toxic corrosion inhibitor such as Di-Potassium Phosphate is used in fact it is the only corrosion inhibitor found in most RV/Marine antifreeze. Also, since RV/Marine antifreeze is intended to be flushed out seasonally, the corrosion inhibitors are not designed for long-term protection.

RV/Marine antifreeze is not formulated for use in automotive and light/heavy duty vehicles. In these applications, a coolant specifically formulated to protect engines and cooling systems against rust, corrosion and freeze/boil over protection should be used. Motor vehicle antifreeze is intended to protect the cooling system in a car or truck from corrosion for a period of 2-3 years. As a result, the corrosion inhibitors are much more expensive.