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Table of Contents About Prestone Command速 3 Essential maintenance for bus cooling systems

By Colin Dilley, Ph. D.

Maximizing bus engine efficiency

By Colin Dilley, Ph. D.

Optimize antifreeze/coolant change intervals

By Colin Dilley, Ph. D.

Critical areas of cold-weather maintenance 11 By Peter Woyciesjes, Ph. D.

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Prestone Command® It doesn’t matter if you’re rolling through brutal heat or grinding cold – when big rigs go out of commission, money is lost. At Prestone, we know it’s about increasing uptime and decreasing maintenance costs. Prestone has pioneered antifreeze/coolant innovation for the better part of a century. It’s what we do. And we’ve done it again with the Prestone Command® family of products. Our advanced and patented antifreeze/ coolant formulas, additives and testing products deliver the technology and innovation fleets can trust.

Take Command with the Complete Solution Click to learn more about our products.

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Essential maintenance for bus cooling systems By Colin Dilley, Ph.D. Prestone® Technology Center Regardless of size and market channel served, all bus fleets have one thing in common - cooling system maintenance has a huge impact on uptime and the bottom line. Today’s diesel engines are sophisticated, maximizing power and addressing concerns like fuel efficiency and emissions. As a result, they run hotter than ever before and are more expensive to repair. Fleet maintenance managers must constantly test and maintain vehicle cooling systems to ensure engine protection and efficient operation. Seven maintenance essentials Cooling system maintenance can be summarized in seven key thoughts: 1. Know what chemistry is in your cooling system - do not mix silicate and OAT chemistries. 2. Flush coolant when: indicated by testing, change intervals, conducting major cooling system repairs or, in some cases, changing technologies. 3. Fill using a 50/50 mix of concentrate and quality water. 4. Operate at the proper coolant levels, topping off using prediluted coolant of the correct coolant type. 5. Ethylene Glycol concentration should not fall below 40 percent or exceed 70 percent by volume. 6. Test regularly for appropriate additive levels, coolant concentration and contamination, adjusting as indicated. 7. Only utilize coolant from a reputable manufacturer that meets industry standards. Beyond temperature Antifreeze/coolant (AF/C) plays a much larger role in engine performance than just providing freezing and boilover protection. It acts as a heat transfer fluid, removing heat from the engine to allow the engine combustion process to run efficiently. The water-ethylene glycol mixture in coolant provides these properties, but is naturally corrosive. Corrosion can degrade the effectiveness of a cooling system by blocking the heat exchange in the radiator and heater core and causing water pump failures. To protect the cooling-system components, manufacturers add corrosion inhibitors (inorganic and/or organic salts and other chemicals). Corrosion can happen even faster when AF/C is depleted because inhibitors are no longer at effective levels to protect against corrosion. It’s imperative to keep coolant topped off at appropriate levels at all times for optimal protection. When used as directed and properly maintained, AF/C is designed to provide efficient heat transfer, and protection against temperature extremes, corrosion (rust, pitting corrosion, 4

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Use of quality antifreeze coolant and regular testing will ensure the best possible protection and efficient operation of a heavy-duty engine.

liner cavitation and surface corrosion), silicate gel deposits, hard-water scale, and cooling-system component failure. Testing The only way to find out if you have the correct AF/C concentration, with the proper amount and type of inhibitors, is to test regularly. AF/C concentrations should be adjusted to the ranges dictated by the temperatures in the geographic region in which your fleet operates, never falling below 40 percent or above 70 percent by volume mixture of ethylene glycol to water (at most elevations). If the ethylene glycol concentration drops below 40 percent, you no longer have adequate inhibitor protection or against freezing in sub-zero (-12°F) temperatures. Conversely, when ethylene glycol levels exceed 70 percent, it can create AF/C slush and leave an engine with little extreme-temperature protection. Refer to OEM specifications for the recommend usage concentrations and other supporting information. Water quality is vital and should be tested to prevent scale build-up or corrosion from varying levels of calcium, magnesium, chloride and sulfate. Appropriate concentrate/water ratios within the cooling system help ensure engine operational efficiency, and can be measured a number of ways. Prestone Command® offers three different solutions: Test Kits This laboratory analysis program tests fluids and provides a detailed report on freezing/boiling points, total dissolved solids, pH, hardness and coolant buffering capabilities at different levels based on Prestone Command technology. • AFC100-TK2 - Designed for analysis of conventional low silicate heavy duty (IAT) coolants • AFC110-TK3 - Designed for analysis of IAT and organic acids heavy duty (NOAT, OAT, HOAT) coolants • AFC110-TK5 - Designed for Advanced Coolant Condition Monitoring for all coolant technologies Test Strips Specifically designed Test Strips will assist in determining pH, glycol concentration and allow you to check for: • Water Quality • Nitrite and Molybdate Levels • Nitrite Levels • Corrosion inhibitor (Organic Acid) Levels busridemaintenance.com

Wet cylinder liner cavitation can occur when antifreeze/coolant loses its ability to protect engine components from damage.

From ethylene and propylene glycol concentration levels to visual inspection for rust and sediment presence, the new Prestone Command® line of coolant tests provide convenience and user-friendly operation to determine key characteristics of AF/C conditions.

Refractometer The go-to tool for measuring the freeze/boilover protection of ethylene glycol based AF/C and urea content in DEF. • Measures concentration and freezing temperature of ethylene and propylene glycol-based coolants • Easy-to-use, customerfriendly portability that provides a wide-range measurement • Provides a dual scale and temperature compensation Mixing Coolants While the recommended OEM coolant chemistry is always the best choice during top-offs, it is essential to understand that mixing the different chemistries ESI, OAT, and NOAT together can in fact decrease the corrosion effectiveness of the final chemistry. Some of these technologies are more compatible when compared to others with respect to freezing and boiling protection, but in corrosion protection they protect in different ways. Different technology can effectively be mixed up to a 20% dilution and still provide proper corrosion protection. However, accurately monitoring this definitive percentage across many fleet vehicles is an enormous challenge. It is easier and safer for a fleet to select one coolant technology and follow it through. According to the Trucking Maintenance Council (TMC) RP365, mixing of inhibitor technologies or mixing products within the same technological category over 20% may alter the original level of chemical protection of a coolant. This can shorten the service life of both the coolant and cooling-system components. Improperly maintained coolant can lead to cooling system and cooling-system component failures such as: • Wet Cylinder Liner Cavitation • Rust/Corrosion of the Cooling System Metals • Hard-Water Scale • Silicate Drop-Out Deposits One of the other potential outcomes of mixing chemistries in a top-off is a final chemistry that becomes far more difficult to test and to secure accurate readings. In cases where chemistry mixing has occurred, the safest practice would be to initiate a complete coolant flush and fill. Conclusion Like the engines it protects, antifreeze/coolant has become much more sophisticated. If properly maintained, it provides efficient heat transfer for the engine, protection against temperature extremes, cooling system corrosion protection, and more. Fleets should look for a quality AF/C like Prestone Command to protect their cooling system and in turn, their investment.

Temperature, Elevation, Water Quality Affect AF/C Performance By Colin Dilley, Ph.D. Prestone® Technology Center Antifreeze (Ethylene Glycol Base) and good quality water* are mixed at a 50/50 ratio to lower the freeze point of the cooling system to -34º F (-37º C) and raise the boiling point of the system to 265º F (129º C), pressure measured with use of 15-lb pressure cap.

Antifreeze (Ethylene Glycol Base) and good quality water should be mixed at the appropriate ratio indicated by OEM specifications.

Above 5000 ft elevation antifreeze/ coolant concentration should be maintained at a 55-60% antifreeze/coolant to water mixture to reduce the chance of boilover. Refer to OEM specifications for more information. *per ASTM and TMC recommendations

Colin Dilley, Ph.D, is the vice president of technology for Prestone Products Corporation. Prestone Products Corporation manufactures and markets Prestone® antifreeze/coolant and related products. For more than 85 years, the Prestone name has provided customers with high-quality products, including one of the leading brands of antifreeze/coolant. Visit www.PrestoneCommand.com

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Maximizing bus engine efficiency By Colin Dilley, Ph.D. rovide freezing protection to prevent freezeups or non-starts P in the lowest temperatures. • Inhibit corrosion for all cooling-system metals through a wide range of temperatures and operating conditions. • Check the coolant concentration to ensure the correct freeze point/boil point protection is being maintained for the climate in which the vehicle will be operating. •

The very best AF/Cs do more than simply keep the engine from freezing up in cold temperatures or overheating in extreme heat, they also fight metal corrosion within the engine.

The very best AF/Cs not only keep the engine from freezing up in cold temperatures and overheating in extreme heat, they also fight metal corrosion within the engine.

With cold weather approaching, fleet professionals will check antifreeze/coolant (AF/C) as a safeguard against extreme cold and freezing, but AF/C plays a much larger role in engine efficiency. The cooling system affects the performance of other vehicle systems and proper maintenance will ensure the best possible operating efficiency, in any season. If the cooling system is unable to operate efficiently, the heavy-duty vehicle’s emissions, fuel economy, horsepower and durability of engine components could be compromised. How does AF/C protect the engine? The essential tasks for any cooling system are: • Provide efficient heat transfer to control critical metal temperatures. • Increase the cooling index to help prevent boilover and overheating failures. 6

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Fighting corrosion Rust and corrosion can ruin the efficiency of a cooling system, putting the entire engine at risk. With a myriad of different metals making up any heavy duty engine, it is important to understand the need for inhibitors in the coolant to fight rust and corrosion across all metal surfaces. Cooling-system problems can result from the deterioration of any material within the engine, or supporting systems. Engines cannot operate efficiently with deposits on metal surfaces, which slowly impair an engine’s performance. The correct mixture of coolant with the proper amount and type of inhibitors will guard against corrosion (Original Equipment Manufacturers provide guidelines for coolants in their engines). As the operation of the heavy duty engine consumes corrosionfighting additives, Supplemental Coolant Additives (SCA) must be periodically added to systems with conventional IAC and HOAT coolants to maintain effective corrosion protection. Extended Life OAT and NOAT coolants do not require SCAs. The inhibitor package within these different chemistries does not determine the level of freeze or boilover protection in the coolant. These inhibitor packages are focused solely on corrosion protection. In the event that metal components become corroded and AF/C flow becomes restricted for any reason, the system’s ability to adequately cool or transfer heat from the key components diminishes considerably. This inefficiency can eventually lead to costly engine damage, both in terms of downtime and repair expense. busridemaintenance.com

The following additives are known as effective corrosion inhibitors: ilicate/Silicone — provides protection for the aluminum S components in a vehicle’s cooling system • Triazoles/Thiazoles — protect copper and brass components • Sodium Molybdate — protects ferrous metals, cast iron and steel from corrosion • Nitrate — protects against pitting and crevice attack in aluminum components • Nitrite — prevents cylinder-liner pitting in cast-iron components in heavy duty engines • Organic Acids — used as a replacement for other inhibitors, such as silicate/silicone, nitrites, nitrate, phosphates, amines and borates • Anti-Foam — added to coolant to minimize foaming when the coolant is mixed with water •

Prestone Command offers a full solution for heavy duty antifreeze-coolant that provides easy-to-use testing and quality refill options for AF/C additives and extenders to ensure optimal operating efficiency and cooling system reliability.

Prestone Command offers a full solution for heavy duty antifreeze-coolant that provides easy-to-use testing and quality refill options.

The complete Prestone Command line of AF/C formulations meet or exceed the performance requirements of many industry specifications. • Heavy Duty Nitrite Free Extended Life Antifreeze/Coolant (ELC) – this yellow-dyed antifreeze/coolant is an Organic Acid Technology (OAT) intended for use and compatibility with any OAT Extended Life heavy duty antifreeze/coolant in any diesel powered commercial vehicle engine or stationary engine with aluminum or other engine metals. Premium longlasting inhibitors provide up to 600,000 miles/12,000 hours of protection against temperature extremes, rust, corrosion, scale and premature water pump failure. The phosphate- and boratefree formulation provides long lasting inhibition and corrosion protection, protecting aluminum and all other engine metals. This formulation is also available in a 50/50 formulation for convenient top-offs. •

eavy Duty Extended Life Antifreeze/Coolant (ELC) H — this red-dyed patented antifreeze/coolant is a blend of ethylene glycol and a specially formulated Nitrited Organic

Acid Technology (NOAT) inhibitor package that is silicate-, phosphate- and borate-free and designed for heavy duty cooling systems. It is formulated for a service life of 600,000 miles or 12,000 hours, when an extender is added at 300,000 miles or 6,000 hours. This ELC is compatible with other ELC products as well as conventional coolants, though its extended life benefits will be reduced in those circumstances. This formulation is also available in a 50/50 formulation for convenient top-offs. •

eavy Duty Extended Service Interval SCA Pre-Charged H Antifreeze/Coolant (ESI) — this purple-dyed antifreeze/ coolant is a blend of ethylene glycol and a specially formulated inhibitor package that has been designed for heavy duty coolingsystem applications. This ESI coolant is compatible with any conventional heavy duty coolant and all filter technologies, and will eliminate the initial pre-charge of SCAs on new vehicles and recharged systems. This formulation is also available in a 50/50 formulation for convenient top-offs.

Efficiency gets help from AF/C testing There are a few key cooling-system maintenance essentials that should be considered in order to ensure the efficient operation of an engine: • Test coolants regularly for appropriate additive levels. • Only utilize coolant that meets industry standards and performance requirements. • Top off cooling systems using pre-diluted coolant and maintain additive levels at regular service intervals with liquid additives. Conclusion The maintenance on a heavy duty engine requires an understanding of the entire cooling system that ties precision and power together. Antifreeze/coolant choices, and the intervals chosen to replenish them, are important for fighting enginecomponent corrosion and other ailments that deteriorate the heavy-duty engine’s efficiency and overall productivity. Coolant decisions can have a profound effect relating to time spent on the road – or time spent in the garage. To safeguard a heavyduty engine’s horsepower, fuel economy, emissions and overall durability, these decisions should be made based on the integrity of the supplier who stands behind the quality of its products, which have been designed to meet performance requirements and industry specifications. Colin Dilley, Ph.D, is the vice president of technology for Prestone Products Corporation. Prestone Products Corporation manufactures and markets Prestone® antifreeze/coolant and related products. For more than 85 years, the Prestone name has provided customers with high-quality products, including one of the leading brands of antifreeze/coolant. Visit www.PrestoneCommand.com

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Optimize antifreeze/coolant change intervals Modern AF/C formulations are engineered to deliver extended protection By Colin Dilley, Ph.D. For the modern day fleet manager, buses on the road equate to revenue growth, while those in the shop minimize margins and put additional, unnecessary stress on the remaining vehicles. Optimizing change intervals for cooling system maintenance is one way to positively impact the bottom line, but if done incorrectly the long-term cost can significantly outweigh the short-term savings. Before optimizing a heavy duty vehicle’s antifreeze/coolant (AF/C) change interval, it’s important to understand the critical role coolant plays in protecting an engine and the engine manufacturers’ recommended coolant-maintenance intervals. OEs recommend specific change intervals for AF/C to ensure the system operates properly. AF/C producers work with heavy duty engine manufacturers and standards organizations to refine their formulations, with the goal of developing a product that optimizes heavy duty engine performance within the OE guidelines. Further, in order for modern gasoline, diesel and/or Liquid Petroleum Gas (LPG) engines to meet the lofty federal efficiency, exhaust and environmental parameters, engine manufacturers have introduced new engines that are running hotter – especially those that rely on LPG and have Exhaust Gas Recirculation (EGR) system to reduce nitrogen oxide (NOx) emissions. The problems these higher temperatures may cause include possible “hot spots” that can cause pre-ignition; oil degradation; and thermal distortion. These conditions can have an adverse effect on engine performance and lead to premature breakdown or failure. In order to deliver optimal performance, bus engines need to work hand in hand with a cooling system to provide balance between the cooling system’s components and the AF/C in the system. It takes specially formulated AF/C to meet the demands of today’s modern engine platforms. That’s why it is more vital than ever to abide by recommended change intervals, whether from the engine manufacturer or any of the standardization organizations, for AF/C in heavy duty engines. Fleet managers must also be cautious when presented with claims of a “new and improved” AF/C formulation that may not require a change before one million miles of operation, when the highest accepted standard is currently 600,000 miles -- and with most manufacturers recommending 300,000 miles. It makes sense to first step back and assess the risks that may be involved in using a product that veers so far from established norms, in some cases as much as a 70% increase from the manufacturer’s recommended AF/C service life. 8

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This red-dyed patented antifreeze/coolant is a blend of ethylene glycol and a specially formulated Nitrited Organic Acid Technology (NOAT) inhibitor package.

The musts of cooling system maintenance Remember these things when it comes to bus cooling system maintenance: • Understand the engine manufacturer’s coolant requirements and industry standards for coolant performance and change intervals • Always use the recommended coolant at the correct concentration • Test the coolant regularly for proper additive levels and freeze/boilover protection • Maintain proper additive levels and regularly top off coolants at regular service intervals. 1. Understand the engine manufacturer’s coolant requirements and industry standard for coolant performance and change intervals First, OEM recommendations should always be consulted. Second, Prestone’s U.S.-based technology center works closely with major engine manufacturers and standardization organizations to create technologically advanced, patented formulations that meet or exceed their requirements. Prestone Command® is available in three heavy duty formulations: • Heavy Duty Nitrite Free Extended Life Antifreeze/ Coolant (ELC) – this yellow-dyed antifreeze/coolant is an Organic Acid Technology (OAT) with premium long-lasting inhibitors that provide up to 600,000 miles/12,000 hours of protection against temperature extremes, rust, corrosion, scale and premature water pump failure. busridemaintenance.com

Extreme temperatures on both ends of the spectrum call for optimum antifreeze/coolant change intervals.

• Heavy Duty Extended Life Antifreeze/Coolant (ELC) — this red-dyed patented antifreeze/coolant is a blend of ethylene glycol and a specially formulated Nitrited Organic Acid Technology (NOAT) inhibitor package and is formulated for a service life of 600,000 miles or 12,000 hours, when an extender is added at 300,000 miles or 6,000 hours. •H eavy Duty Extended Service Interval SCA PreCharged Antifreeze/Coolant (ESI) — this purple-dyed antifreeze/coolant is a blend of ethylene glycol and a specially formulated inhibitor package that has been designed for heavy duty cooling-system applications, and is compatible with any conventional heavy duty coolant and all filter technologies.

3. Test the Coolant Regularly For Proper Additive Levels And Freeze/Boilover Protection Testing the coolant concentration (mixture of glycol, water and inhibitors) is an important part of winter engine management and is critical for optimal cooling system performance between change intervals. If the coolant concentration dips below 30% there will be little to no protection from cold weather temperature extremes. When glycol levels exceed 70%, it can leave an engine with virtually no extreme temperature protection and it can potentially create slushing of coolant. If the glycol concentration is too rich or too low, not only can freezing and boilover protection become a problem, but the correct level of inhibitors necessary to protect the essential engine components can become a matter of concern. The Testing Solution The Prestone Command solution for AF/C testing includes Test Kits, Test Strips, and a hand-held refractometer to provide convenient options for and different levels of AF/C analysis. Prestone Command® Test Kits Prestone Command offers a complete fluid testing, training and consulting program to complement its trusted antifreeze/coolant family. Prestone Command offers three different test kits to meet the various challenges equipment might encounter. • AFC100-TK2 Designed for analysis of conventional low silicate heavy duty (IAT) coolants • AFC110-TK3 Designed for analysis of IAT and organic acids heavy duty (NOAT, OAT, HOAT) coolants • AFC110-TK5 Designed for Advanced Coolant Condition Monitoring for all coolant technologies

2. Always use the recommended coolant at the correct concentration A disproportionate ratio of AF/C to water in the mix can mean the heat exchange between the AF/C and the engine cooling system will not be efficient, putting additional stress on the cooling system components that could lead to premature failure. This can also lead to additional stress on the other functional fluids under the hood, including engine oil as well as transmission and power steering fluids. OEM recommendations should always be consulted, but a general recommendation of a 50/50 ratio of concentrate-to-water will provide the system a boiling point up to 265°F and freeze point protection to -34°F. To optimize the performance of the specially blended inhibitors in an AF/C, it must be accurately diluted with good quality water that has been tested for pH and impurities.

Prestone Command® Test Strips Specifically-designed Test Strips will assist in determining pH, glycol concentration and allow you to check for: water quality, Nitrite and Molybdate levels, Nitrite levels, and corrosion inhibitor (Organic Acid) levels Prestone Command® Refractometer Measuring concentration and the freezing temperature of ethylene and propylene glycol-based coolants, the refractometer will provide: • E asy-to-use portability that offers a wide-range of measurements • Dual scale and temperature compensation

4. Maintain Proper Additive Levels And Regularly Top Off Coolants At Regular Service Intervals. So you’ve tested your AF/C and ensured that you have the proper additives and coolant levels in place, but that doesn’t mean you can check off cooling system maintenance until the busridemaintenance.com | BUSRIDE MAINTENANCE

recommended change interval arrives. Hoses will leak, coolant levels will change, inhibitors can precipitate out. It’s a cost of doing business when operating heavy duty vehicles. This final “must” of cooling system maintenance actually directs you back to the prior steps, as selecting the highest quality AF/C products, testing and replenishing is an ongoing cycle that will ensure operating efficiency and optimal performance. The Prestone and Prestone Command® line of antifreeze, additives and testing products deliver the technology and innovation fleets can trust to protect engines from extreme onroad conditions and corrosion while increasing uptime. Conclusion To safely optimize change intervals, a thorough maintenance plan needs to be put in place to ensure that all of the vehicle’s components are operating at their utmost efficiency and effectiveness. This plan will pay big dividends in the form of asset reliability, extended equipment life and minimized downtime by identifying minor problems before they become major failures. Through its industry experience, research and development, and the creation of its Prestone Command® Extended Life Coolant formulation, Prestone stands ready to work with fleet operators to responsibly optimize their AFC change intervals, while not jeopardizing the health and performance of the engines in their vehicles. Specifically-designed Test Strips will assist in determining pH, glycol concentration and allow you to check for: water quality, Nitrite and Molybdate levels, Nitrite levels, and corrosion inhibitor (Organic Acid) levels.

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Colin Dilley, Ph.D, is the Vice President of Technology for Prestone Products Corporation. Prestone Products Corporation manufactures and markets Prestone® antifreeze/coolant and related products. For more than 85 years, the Prestone name has provided customers with high-quality products, including one of the leading brands of antifreeze/coolant. Visit www.PrestoneCommand.com

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Critical areas of cold-weather maintenance Extreme winter temperatures require cooling system attention By Peter Woyciesjes, Ph.D. Prestone® Technology Center

As we face the winter of 2016, we can reflect back on the prior year as the poster child for the importance of preparedness. States west of the Mississippi river experienced unusually warm weather. Conversely, February 2015 was one of the coldest Februarys on record in many Midwest and Northeast cities. All but four states east of the Mississippi placed within their 10 coldest Februarys since 1895. Arctic sub-zero temperatures and double-digit wind-chills left many busses stranded or with incapacitated equipment. For many of those stranded during the winter cold snap, it was decisions made about what to do (or what not to do) with their antifreeze/coolant systems that may have sealed their fate. WINTER’S COMING At a glance, coolant maintenance may seem to be as simple as pouring in new coolant. However, given the vast number of new antifreeze/coolant technologies and formulations, making decisions regarding their maintenance is a very serious matter that can potentially affect the bottom line of any fleet. Ask anyone who may have been stranded or stuck in the shop during any brutal winter cold snap. The primary components of antifreeze, both glycol and water, can freeze; however, a combination of both has the ability to prevent freezing to a lower temperature. While recognizing glycol levels in antifreeze/coolant is essential to maintaining a properly operating heavy-duty vehicle, it is by no means less of a concern than corrosion within the engine. Responsible testing recognizes coolant has

key protective characteristics that can minimize additional issues such as corrosion or scaling buildup. During extreme temperatures, fleets are not thinking so much about corrosion protection as they are trying to make sure the necessary percent of glycol is correct in their formula. Corrosion protection is a daily concern for the heavy duty engine, and freezing concerns tend to be seasonal. INSPECTION ESSENTIALS “A solid practice for antifreeze/coolant maintenance would be to take the opportunity to check the overall effectiveness of coolant while also checking for seasonal freezing protection,” says Peter Woyciesjes, worldwide research development and engineering coolants manager for Prestone.

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There are three steps for such an inspection: 1. Test your glycol for freeze-point. 2. Test for inhibitors to make sure you’re still getting the correct corrosion protection. 3. Make sure you’ve got the right volume in your cooling system so there are no air pockets. “Air entrapment is a serious problem for any engine,” Woyciesjes says. “Seasonal cold weather testing is the ideal time to make sure your engine is full and topped-off.” A routine loss of coolant due to leaks and other maintenance issues can be expected. In these cases, topping off with the appropriate 50% pre-diluted coolant is ideal. If an engine has encountered cooling system failure, draining and replacing the coolant with a fresh fill of a quality coolant is recommended. “I would not recommend that coolant collected from a leaking system or a system being drained be reused,” Woyciesjes says. “Given everything within the engine that relies on the cooling system, it is much safer to refill the system with a fresh batch of antifreeze/coolant.” COMPONENTS AT RISK These are some of the major bus-engine components that can become compromised if incorrect levels of AF/C concentrations or corrosion inhibitors are present: • Radiator • Heater Core • Wet Sleeve Liner • Coolant Pump • Block • Cylinder Head • Thermostat • Hoses • Gaskets • Oil Cooler • Super/Turbo Charger • Sensors • EGR Valve • Control Valve

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In addition to the actual engine components, the metal surfaces that make up the entire bus engine can be negatively affected by incorrectly managed levels of coolant. Typical cooling-system metals that can be affected are cast iron, steel, cast aluminum, aluminum alloys, brass, copper and solder CAB flux. Antifreeze/coolant should: • P rovide freezing protection to the lowest temperature encountered. • Provide effective inhibition of corrosion for all cooling system metals through a wide range of temperatures. • Provide efficient transfer of engine heat to help control critical metal temperatures. • Maintain optimum engine temperature for fuel and lubrication efficiencies. • Increase the cooling index to help prevent boilover and overheating failures. • Unless routine testing reveals a change is needed earlier, following engine manufacturer guidelines is the best practice for ensuring appropriate antifreeze/coolant protection. Knowing the challenges that winter driving can present for bus fleets, the Prestone Command® line of antifreeze, additives and testing products have been formulated to deliver the technology and innovation fleets can trust to protect engines from extreme on-road conditions and corrosion while increasing uptime. CONCLUSION In many areas of the country, driving in severe cold and snow are an unavoidable fact of life. Bus fleets of all types have schedules that must be met and the only way they can avoid breakdowns that will inconvenience their riders is if their heavy duty engines are maintained properly. While it’s true that effective antifreeze/ coolant maintenance is not just a seasonal concern, winter’s wrath and the extreme demands of harsh weather always elevate the importance of cooling system maintenance to the forefront. Peter Woyciesjes, Ph.D, is the Worldwide RD&E Manager, Coolants at Prestone Products Corporation. Prestone Products Corporation manufactures and markets Prestone® antifreeze/coolant and related products. For more than 85 years, the Prestone name has provided customers with high-quality products, including one of the leading brands of antifreeze/coolant. Visit www.PrestoneCommand.com.

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