Coolant Requirements for Cummins Engines – Please follow up with Cummins for and changes.
Service Bulletin Number
|Cummins® Coolant Requirements and Maintenance
This Service Bulletin supersedes prior Service Bulletins concerning Cummins Inc. coolant requirements and maintenance; replace those Service Bulletins with this one.
This Service Bulletin outlines the proper application and maintenance of coolant for all Cummins® engines, including gaseous fueled engines. It also updates and simplifies Cummins Inc. recommendations and guidelines for the end user.
Summary of Recommendations
Cummins Inc. cooling system general recommendations are listed below. These recommendations apply to both Standard Service Intervals and Extended Service Intervals. See Section 2 – Standard Service Interval or Section 3 – Extended Service Interval for complete instructions.
Definition of Terms
Section 1 – Introduction
Cummins Inc. coolant recommendations have evolved over time to reflect changes in diesel engine and coolant technology, environmental regulations, and customer needs.
Since 1995, Cummins Inc. has recommended the use of only fully formulated coolants meeting ASTM D6210/The Maintenance Council RP 329 (ethylene glycol) and The Maintenance Council RP 330 (propylene glycol) specifications.
However, Cummins Inc. has recently discovered significant weaknesses in some coolants meeting these ASTM specifications. Therefore, a new Cummins Engineering Standard, Cummins Engineering Standard 14603, has been developed to make sure coolant used in Cummins® engines will meet the requirements of all engine components. See Attachment 2 for more information on Cummins Engineering Standard 14603.
Cummins Inc. guidelines prior to 1995 permitted the use of fully formulated antifreezes/coolants meeting ASTM D6210, but primarily addressed the use of partially formulated products meeting ASTM D4985 or GM 6038M, which were referred to as “heavy duty” based on the low-silicate content. These partially formulated coolants contained buffering compounds and corrosion inhibitors, but did not provide liner pitting and scale protection. To provide total heavy-duty cooling system protection, a mixing process was required to add SCA. This mixing process provided opportunity for human error, which often resulted in liner or block pitting from under-concentration during initial fill or SCA dilution during top-off of the cooling system. Because of these issues, the use of partially formulated antifreezes is unacceptable.
Fully formulated antifreezes are ideally suited for topping off cooling systems, but do not eliminate the need for additive replenishment. Routine additive replenishment has always been required to offset normal additive depletion processes.
During normal additive replenishment, it is possible to achieve an additive concentration that is higher than desired. This is because Cummins Inc. recommended replenishment rates have been aimed to compensate for coolant loss. If no coolant loss is experienced, gradual Extender/SCA concentration increase is possible. Overconcentration can be avoided by monitoring with a test kit.
However, the use of test kits to maintain a concentration near the minimum side of the acceptable range has never been acceptable nor recommended. This practice is responsible for many pitting failures and should not be followed.
Coolant Performance Characteristics
Table 2 below lists the various types of coolants and the performance characteristics of each. As mentioned earlier in this section, only fully formulated antifreeze/coolant meeting Cummins Engineering Standard 14603 is recommended for use in Cummins® engines.
Topping Off and Dilution of Cooling Systems
Coolant loss can lead to dilution of corrosion and liner-pitting protection additives due to incorrect top-off practices. This is the root cause of most cases of liner-pitting. The top-off process is simplified by the use of fully formulated antifreezes and coolants because SCA addition is not required when topping off the system. Even small leaks at the hose clamps, radiator cores, cylinder head gaskets, and water pumps result in significant coolant loss over time. Dilution of critical additives is avoided, regardless of the amount of coolant loss, by using fully formulated products for system top-off.
Standard Service Interval Coolant versus Extended Service Interval Coolant
Both types of coolant follow the same general test schedule:
The advantage to using an extended service interval coolant is that typically the coolant only needs additive replenishment and filter change (if equipped) once per year, compared to the standard service interval where the additive and filter (if equipped) is replenished at each lubricating oil change interval. Coolant additives are not to be used with organic acid technology (OAT) coolant.
Section 2 of this bulletin details the standard service interval and Section 3 details the extended service interval.
If you have any questions about information in this bulletin or would like more information, please contact 1-800-DIESELS.
Section 2 – Standard Service Interval
This section outlines the recommended maintenance practices for cooling systems when using a standard service interval.
For an engine using standard service interval coolant, the additive and glycol levels must be tested once every 6 months.
The following steps are required to comply with Cummins Inc. recommendations for initial filling and maintenance of cooling systems.
Test the SCA level a minimum of twice a year.
Section 3 – Extended Service Interval
This section covers the requirements for coolant products that provide extended service maintenance intervals. Beginning in January 2013, all Light Duty, Midrange, and Heavy Duty engines are extended life organic acid technology (OAT) coolant compatible, and as a result the coolant filter is optional.
Extended service interval coolant is defined as a coolant capable of a minimum general routine service interval of 240,000 km [150,000 mi], 4000 hours, or 1 year, whichever occurs first. It must be noted that organic acid technology (OAT) coolants are generally capable of extended service intervals ranging from 500,000 km to 1,000,000 km [300,000 mi to 600,000 mi] or 6000 hours to 7000 hours. Follow maintenance guidelines recommended by the coolant manufacturer.
Successful usage of extended service interval products will be possible only if a systematic approach to coolant maintenance is followed by the user. This means using the extended service interval system of coolant products for all coolant maintenance at the fleet shop as well as on the road. Use of the proper coolant is vital for successful extended service interval maintenance. If control of top-off can not be accomplished, do not consider extended service and use the standard service interval as described in Section 2. Coolant must meet the requirements stated in this section.
It is preferred and recommended for all Cummins® engines to top off only with fully formulated coolants which meet Cummins Engineering Standard 14603. See Attachment 2 for more information on Cummins Engineering Standard 14603. However, MidRange products, including any Cummins® engine displacing less than 10 liters [610 C.I.D.], may top off with fully formulated coolants meeting a minimum requirement of ASTM D6210.
Cummins Inc. recommends Fleetguard® antifreeze/coolant. All Fleetguard® coolants meet the requirements of Cummins Engineering Standard 14603. See Table 3 for recommended antifreeze/coolant.
*Product availability varies by region. Please visit www.cumminsfiltration.com or contact your local customer assistance for more information.
**To maintain the protection provided by Fleetguard coolants, the proper level of inhibitor must be present. This is typically achieved by topping off the cooling system with premixed Fleetguard coolant. The user is responsible for ensuring proper additive levels and coolant pH through the use of test strips and the addition of additives or new coolant if necessary. The recommended test intervals are as follows: OAT coolants – 300,000 miles, 6,000 hours, or 1 year; Hybrid coolants – 150,000 miles, 4,000 hours, or 1 year; Conventional coolants – Every oil drain interval or 1 year. The shortest of recommended hours, miles, or 1 year should be used as the test interval. The test interval is a precautionary recommendation intended to prevent maintenance and engine problems from causing progressive, severe engine damage.
Extended Life Coolants (ELC) Plus Silicates
Many commonly available extended life coolants (ELC) do not meet the elastomer compatibility requirements of CES14603, and therefore, are not recommended for use by Cummins. These coolants are only acceptable for use if the initial coolant fill requirements were met by the vehicle’s original equipment manufacturer (OEM), including the addition of silicates. Cummins recommends contacting the coolant supplier to request a copy of their CES14603 approval letter from Cummins if unsure about compatibility.
Heavy-Duty and High Horsepower engines requiring overhauls or repairs involving the replacement of the following components that are using OAT coolants not meeting CES 14603, must discard the original coolant and replace with new.
If the replacement coolant does not meet the elastomer compatibility section of CES14603, the initial coolant must be treated by adding 0.24 liters [ 8 fl-oz ] of liquid silicate fluid for every 45 liters [ 12 U.S. gal ] of total coolant system volume. It is critical to not over treat the coolant with silicate fluid. If over-treatment is suspected, drain the cooling system and discard the coolant filter (if equipped). Clean the cooling system immediately. Symptoms of silicate over-treatment can be thickened coolant in the lower radiator tank, water pump seal leakage soon after silicate addition, reduced heater output and/or elevated engine temperatures. Use Fleetguard® Restore Cooling System Cleaner at the rate of 3.8 liters [ 1 U.S. gal ] per 38 to 45 liters [ 10 to 12 U.S. gal ] of water. Do not use Fleetguard® Restore Cooling System Cleaner with normal engine coolant.
To obtain order forms or ask questions relative to ordering the silicate fluid:
Extended Service Maintenance
Liner Pitting Protection Additive Levels Required at Initial System Fill
NOTE: Nitrite and molybdate are not used in Fleetguard® OAT coolants for cylinder liner pitting protection but are used in other Fleetgaurd® products. Follow the manufacturers’ recommendations specific to each product. Table 4 provides target concentrations for initial fill of coolants that use nitire and molybdate to provide cylinder liner pitting protection.
1: Concentrated antifreeze/coolant levels are double the premixed levels.
2: A combination of nitrite (NO2) and molybdate (MoO4) can not contain less than 500 ppm of either additive
Extender/Extended Service Additive Levels
Test the SCA level a minimum of twice a year.
The Extender replaces the additives in the coolant that are lost due to depletion. It can be added as a liquid directly to the coolant or as a solid contained in a coolant filter.
Cummins Inc. recommends using a Fleetguard® ES™ slow release filter or ES™ Extender liquid.
The Extender must contain sufficient liner-pitting additives to increase the levels of nitrite or nitrite plus molybdate in the engine coolant by the following amounts:
A combination of nitrite and molybdate can not contain less than 200 ppm of either additive.
Liquid Extenders typically have a shelf life of at least 2 years from the time of manufacture when stored at temperatures ranging from -7° to 55°C [19° to 131°F].
Solid material, liquid turbidity, or layering at the top of the liquid is allowed if it will dissolve and disperse by stirring the solution and warming it to a temperature between 2° to 67°C [36° to 153°F].
Solid, slurry, and paste forms of Extender must dissolve completely in hot engine coolant. They must be formulated and packaged to prevent chemical or physical change during storage temperatures ranging from -7° to 55°C [19° to 131°F] regardless of humidity.
Section 4 – Unacceptable Maintenance Practices for Cooling Systems
NOTE: Some OAT coolants use high levels of organic acids for liner pitting protection and do not use nitrite and or molybdate. Therefore, these coolants do not have SCA numbers.
Unacceptable Practices – The following practices are considered unacceptable and may lead to engine failure.
Section 5 – Recommended Maintenance Practices for Cooling Systems of A, B, D, and F Series Engines
The A and B Series engines normally do not require Extender/SCA because they do not normally experience cylinder bore/liner cavitation corrosion. Also, the A and B Series engines do not have an integral coolant filter.
Coolant maintenance requirements for the Cummins® B series engines depend on the application.
Light duty applications can use coolant meeting ASTM D3306 and follow the maintenance schedule in the appropriate Owners manual. However, if ASTM D3306 antifreeze is used, it must additionally meet the elastomer capability section of Cummins Engineering Standard 14603.
Use of fully formulated antifreeze/coolant in this engine is acceptable but not required. If fully formulated antifreeze/coolant is used, it must meet a minimum requirement of ASTM D6210.
The F-Series engines must use coolant meeting ASTM D3306, except North America Industrial F-Series which may also use coolant meeting ASTM D6210. The F-Series must follow the maintenance schedule in the appropriate Owners or Operation and Maintenance Manual.
Section 6 – Coolant Testing
Coolant testing is required for two reasons:
Coolant testing for additive and glycol levels must be performed at least twice a year. The coolant must also be tested for replacement limits every 240,000 km [150,000 mi], 4000 hours, or once a year, whichever occurs first.
Additive and glycol testing is also recommended when the following occur:
Coolant Replacement Limits
Table 5 below lists the limits for various coolant contaminants.
1: Concentrated antifreeze/coolant levels are double the premixed levels.
Bromide is typically a contaminant from radiator flux and fluoride is a contaminant from brazing flux. Both bromide and fluoride are corrosive especially to aluminum parts.
If the coolant does not meet the replacement limits of sulfate, chloride, or pH, it must be drained and replaced with new coolant meeting Cummins Engineering Standard 14603. However, if the coolant is contaminated with oil, fuel, grease, solder bloom, silica gel, rust, or scaling, the system must be drained, cleaned, and refilled. See Section 11 for details on cleaning the cooling system.
Coolant Testing Kits
Coolant testing and monitoring are useful tools for tracking and controlling coolant condition and performance. The methods available for testing coolants include field test kits, portable refractometers, and coolant analysis programs. Cummins Inc. recommends using the following Fleetguard® products:
Coolant Additive and Glycol level testing:
Coolant testing for contamination/replacement limits:
Coolant Freeze Point Testing
For use with ethylene and propylene glycol coolants only.
For use with glycerin coolant only.
Coolant analysis program.
The Three-Way™ heavy duty coolant field test kit is appropriate for testing nitrite-molybdate formulations, such as Fleetguard® DCA-4 as well as nitrite formulations such as Fleetguard® DCA2 (Fleetcool).
Fleetguard® Quik-Chek™ test strips will detect contamination levels that indicate replacement of the coolant is required.
The Monitor C™ program can evaluate most new or used coolant formulations.
Field test kits offer the benefit of on-site measurements and are designed to approximate Extender/SCA levels and freezing points. When required, freezing points can be more accurately determined with on-site refractometer readings.
When using the Fleetguard® Three-Way™ heavy duty coolant test kit, it is important to follow the instructions provided in the kit. Contact Cummins® Filtration Technical Assistance at 800-223-4583 or www.Cumminsfiltration.com for additional information.
Because the kit measures nitrite and molybdate separately, it can reliably measure both Fleetguard® SCA formulations as well as most competitive SCA formulations. Cummins Inc. recommendation for a nitrite-molybdate formulation for pitting protection is explained in Attachment 1 – Summary of Coolant Additive Technology.
Correct interpretation of laboratory data can provide additional guidance in coolant treatment effectiveness and early warning detection. Interpretation and further treatment action(s) are generally provided with laboratory results. Therefore, laboratory testing is typically very cost effective for the long term when used to optimize cooling system performance and life. However, it must not be used as a method for minimizing treatment.
Coolant analysis programs are performed in laboratories and offer additional, useful information, but require mailing coolant samples to a laboratory. Laboratory measurements typically include the following:
See Attachment 3 for an example of a Monitor C™ report.
Section 7 – Antifreeze
The primary purpose of antifreeze is to lower the freezing point of the coolant. Additional performance characteristics of coolants that are affected by the use of antifreeze include boiling point and vapor pressure. Antifreeze decreases vapor pressure, which is very beneficial to the reduction of cavitation corrosion liner pitting. This characteristic is the primary basis for Cummins Inc. requirement for increased SCA levels when antifreeze falls below 40 percent by volume.
A 50/50 mixture of antifreeze and water provides optimum boiling and freezing point protection for engines. An antifreeze concentration in excess of 60 percent must never be used, except in arctic climates, since it increases the possibility of forming cooling system gel, which results as silicates precipitate out of solution. However, an antifreeze concentration of less than 40 percent increases the possibility of coolant freezing and liner pitting. Therefore, Cummins Inc. recommends an antifreeze concentration range of 40 to 60 percent.
Fluids presently used in antifreeze are ethylene glycol, propylene glycol and glycerin. Diesel engine antifreeze has primarily used ethylene glycol products because they are less expensive than propylene glycol products. However, some applications require less toxic coolant products and have driven the use of propylene glycol. The comparative properties are similar for ethylene glycol and propylene glycol and are listed below. Properties of pure water are shown for comparison. Properties of glycerin are similar to that of propylene glycol. Glycerin is non-toxic. See Table 8 for properties.
NOTE: Glycerin used in antifreeze must meet ASTM D7640.
Cummins Inc. does not recommend the use of waterless coolant (coolants containing no water). These coolants have different heat transfer properties which can result in hotter engine temperatures. High engine temperatures can thin lubricating oil and cause wear issues. It can negatively affect gasket and seal materials. Cummins Inc. is not responsible for malfunctions or damage resulting from what Cummins® determines to be abuse or neglect, including, tampering with key engine parts to accommodate such products. Any unauthorized modifications could void warranty.
Section 8 – Treated Water Coolant
For purposes of this document, any coolant mixture with less than 40 percent antifreeze is considered to be “treated water” and requires increased supplemental coolant additives (SCA) as described in this section. Cummins Inc. does not recommend that water treated with additives be used in place of fully formulated antifreeze/coolant. However, it is recognized that certain applications operating only in warm-weather areas may have compelling reasons to use treated water coolants. This section gives some guidance on using treated water coolant in place of antifreeze/coolant if the user chooses to do so.
Customers must also be advised that not using fully formulated antifreeze at 40 to 60 percent glycol levels will reduce the level of engine protection against boil over, liner pitting, water pump cavitation, corrosion, scale and deposit formation, heater core freeze up, and microbial deterioration. Not using antifreeze can also decrease engine and vehicle cooling system component life.
NOTE: Minimum SCA level required for treated water coolant is 0.8 units per liter [3 units per gal] and not 0.3 units per liter [1.2 units per gal] as required in other sections of this bulletin.
Supplemental coolant additive (SCA) levels between 0.8 to 1.3 units per liter [3 to 5 units per gal] must be achieved and maintained through routine replenishment. Replenishment is necessary to make up for depleted SCA chemicals that are spent during normal operation. Incorrect concentration levels can be avoided by usage of the test kit described in Section 6. Cummins Inc. requires the use of quality water (see Section 9) and SCA meeting the ASTM D5752 specification, (see Attachment 2). The greater the water concentration, the more important its purity.
The following steps are required for initial filling and maintenance of treated water cooling systems.
The recommended SCA is Fleetguard®’s liquid DCA4 containing molybdates as well as nitrites. In addition to providing the needed liner and block protection, the engine’s tolerance of excess concentrations of DCA4 is higher as compared to DCA2. Fewer dissolved solids are used in the DCA4 chemical formulation, which reduces the tendency for water pump seal buildup and leakage. SCA formulations that do not contain molybdates, such as Fleetguard®’s liquid Fleetcool (DCA-2), can be successfully used if excess concentrations are avoided.
Section 9 – Water Quality Requirements
Cooling systems perform best with distilled or deionized water. If distilled or deionized water is not available, the quality of the water used must meet all the requirements listed below. Excessive levels of calcium and magnesium contribute to scaling problems, and excessive levels of chloride and sulfate cause cooling system corrosion. If water quality is unknown, it can be tested with the Fleetguard® Monitor C™ program or Water-Chek™ test strip. Water test results can also be obtained from local water utility departments. Test data must show the following elements, and the levels must not exceed the published limits for use in cooling systems.
Fleetguard® Water-Chek™ Test Strip, Part Number CC2609, can be used to determine the quality of make-up and shop tap water. The Water-Chek™ test strip measures hardness, pH, and chloride levels in make-up water.
Section 10 – Maintenance Records
Accurate maintenance records are important. Maintenance programs must be accompanied by accurate record-keeping practices. Records must be capable of supplying the information required for the following:
Routine cooling system maintenance records must include the following information:
Section 11 – Cleaning the Cooling System
Routine cleaning of cooling systems is not recommended. However, inadequate maintenance practices, incorrect use of coolant products, or an engine component failure (such as an oil cooler element) can lead to problems that require cleaning the cooling system. Cummins Inc. recommends the use of cleaning products when one or more of the following contaminants are found in the cooling system:
To remove oil or fuel contamination from a cooling system, a low foaming cleaner specifically designed for oil removal must be used. Fleetguard® Restore™ Heavy-Duty Cleaner is an alkaline based product that has been modified to perform as an oil and grease super cleaner. In addition, it can also effectively remove silicate gelation from a cooling system.
For cleaning poorly maintained or severely contaminated cooling systems, an acid based cleaner is recommended. Fleetguard® Restore Plus™ Heavy-Duty Cleaner is an acid based product that is excellent in removing rust, scale, solder bloom, and other corrosion contaminants from the cooling system.
Table 10 below lists various contaminants and the cleaning performance of each cleaner with respect to those contaminants. The correct cleaner must be chosen based on the type of contamination.
Cooling systems must be cleaned carefully when any of the above conditions are apparent. Overheating can also accompany the above conditions. If the cooling system is overheating, inspect the system to determine if it requires cleaning. It is very important to flush the cooling system of chemical cleaners completely and thoroughly at the conclusion of the cleaning process. This must be done with water and will require more than one flushing to purge the cooling system of the cleaning chemicals. See the remainder of this section for recommended cleaning procedure.
Cleaning Procedure for Removal of Lubricating Oil and Fuel from the Engine Cooling System Using Fleetguard® Restore™ Liquid Cleaner
Prior to cleaning the cooling system, install adequate coolant system draincocks, fittings, and hoses to allow the coolant to drain quickly. The system must be drained immediately upon engine shut down. Therefore, it is suggested that a Tee fitting be installed in the fill line to allow the top tank/expansion tank to drain quickly. In addition, a fabricated Tee connection must be installed in the lower radiator out plumbing if sufficient drain ports are not available to drain the system quickly.
Section 12 – Coolant for Arctic Operation
There are many factors, in addition to engine coolant, that need to be considered when operating Cummins® engines in arctic climates. These are discussed in Cold Weather Operation, Bulletin 3387266, and Operation of Diesel Engines in Cold Climates, Bulletin 3379009. Operation of Diesel Engines in Cold Climates defines arctic conditions as -32°C to -54°C [-25°F to -65°F]. That bulletin recommends use of a 60 percent ethylene glycol antifreeze mixture for coolant for arctic specifications. Cold Weather Operation states that the maximum recommended mixture is 68 percent antifreeze (ethylene glycol).
To update the above recommendations on coolant for arctic operation, a review of the pertinent literature was made and reported recently. The results of the review are:
Section 13 – Recycled Coolants
All documents previously published on recycled coolants are now obsolete. Cummins Inc. requirements for recycled coolant are the same as for new coolant. New and recycled or reclaimed coolant must meet Cummins® Engineering Standard 14603. Some recycled products; based on distillation, dual deionization, or reverse osmosis/electrodialysis of used engine coolant, are capable of meeting Cummins® Engineering Standard 14603. However, glycol reclaimed from the following sources has been found to cause serious engine problems in the field:
Therefore, they would fail the field test portion of Cummins Engineering Standard 14603 and are not approved for use in Cummins® engines.
Section 14 – Nitrite Free Engine Coolant
Many fully formulated diesel engine coolants utilize a nitrite ingredient to provide protection against metallic corrosion and specifically for cylinder liner cavitation protection. This technology, although robust for engines utilizing cylinder liners, can present some disadvantages from a maintenance, materials compatibility, and environmental perspective. Parent bore engines do not necessarily need this ingredient, especially when robust coolants that contain different ingredients for cavitation and corrosion protection (such as those found in Fleetguard® ES Compleat™ OAT coolant) are used.
Coolants that depend on nitrites have a significant disadvantage in that the nitrite ingredient will deplete over time and regular additions of coolant additive extenders are needed to ensure adequate levels of nitrite additive are present in the coolant system.
It is important to draw a clear distinction between uses of Nitrites (i.e. NO2-) and Nitrates (i.e. NO3-). Nitrites are strong oxidizing agents that are beneficial for the prevention of ferrous metal corrosion. However, the breakdown of nitrites can lead to an alkaline environment that is particularly corrosive to the cooling system. Many Original Equipment Manufacturers (OEMs) now prohibit the use of nitrite as part of the coolant formulation and certain geographic locations ban its use. Nitrates are oxidizing agents as well, however less reactive than nitrites and less likely to form alkaline by-products. Nitrates provide acceptable metal corrosion inhibition and are beneficial in coolant formulations where it is utilized.
Nitrites can be detrimental in engines that utilize aluminum in major components such as engine blocks, cylinder heads, and heat exchangers. Under certain conditions, nitrites can form alkaline products which will negatively affect the pH balance in the cooling system and induce corrosion. Engines with major components made from aluminum may require nitrite free coolant. See the corresponding Owners manual and Operation and Maintenance manual for your engine.
Attachment 1 – Summary of Coolant Additive Technology
Antifreeze/coolant concentrate is made up of roughly the following components:
The glycol is present to lower the freeze point and increase the boiling point of the coolant. See Section 7 – Antifreeze, for additional benefits of glycol. The small amount of water is either contained in the additives used or is added to aid the blending of the product. This allows the additive package to better dissolve in the glycol and prevents dropout or precipitation during storage. More detail is given in the following section on the various chemicals and functions of the coolant additive package.
Glycerin can also be used as an antifreeze. However, because glycerin concentrate has a high viscosity, it is usually sold as a 50/50 premix.
Coolant Additives and their Function
A fully formulated antifreeze/coolant will perform the following functions to prevent corrosion and maintain efficient heat transfer. See Section 1 – Introduction for a comparison of the functions of light-duty and heavy-duty antifreeze/coolants.
Supplemental Coolant Additives (SCAs) versus Extended Service Additives
SCAs have been around in the form of chromate based products since the mid 1950’s. The chromate based SCA’s were largely replaced by borate-nitrite products by the mid 1970’s because of chromate’s toxicity. In the mid 1980’s a phosphate-molybdate based product, DCA4 was made available to improve upon the performance of the borate-nitrite products that then dominated the market. The SCAs had three uses.
In the early 1990’s the heavy-duty coolant market had begun to change. Most fleets no longer drained coolant at the recommended 240K mile, or 6K hour recommendation, but continued to use the same coolant until engine rebuild. Fully formulated heavy-duty coolant became more readily available and this resulted in an increase in the length of service intervals. Coolant additive replenishment was separated from servicing of the lube system and pushed out to once per year, 150K miles, or 4K hours. SCA’s are not formulated for long life, extended service operation. Adding SCA to heavy-duty coolant could result in excessive levels of additives in the coolant. Over time, this excessive additive build up or high level of total dissolved solids in the coolant can cause water pump leakage as well as solder and aluminum corrosion.
The first extended service additives, Extended Service Additives or “Extenders”, became available in the late 1980’s and were commonplace by the mid 1990’s. An antifreeze Extender is formulated to replace additive at the rate that it is consumed or depleted. This assumes that the cooling system is being topped up with a fully formulated heavy-duty coolant so that there are little or no issues with additive dilution. The composition of an Extender is based upon the depletion rate of the various components. The Extender contains a larger amount of those additives that deplete quickly and smaller amounts of those additives that are consumed at a lower rate over time. For instance, Extender contains twice the amount of nitrite and half as much phosphate as the regular SCA. This is based on the fact that nitrite depletes faster than phosphate. Extenders are formulated to maintain a proper balance of additives in the coolant over time. However, they will not establish the proper initial additive levels, therefore extenders can not be used to formulate treated water coolant.
“Organic Acid Technology (OAT)” Coolants or “Organic Acid” Coolants
For both OAT and organic acid coolant, organic acids make up the large part of the additive package. However, ethylene glycol or propylene glycol still make up 90 to 95 percent of the antifreeze as with conventional antifreeze. For this reason the heat transfer characteristics and the physical properties such as freeze and boil over protection, specific heat, etc. are very similar to other products in the market.
What is an organic acid? First a chemical is classified as organic if it contains the element carbon as part of its structure. Organic acids are just one of the many classes of organic compounds such as alcohols and carbohydrates. Common organic acids are acetic acid, better known as vinegar, and adipic acid, which is the main ingredient in baking powder. In reality it is the sodium or potassium salts of organic acids that are used as corrosion inhibitors and buffers in engine coolants. The same is true for inorganic acids such as nitric and phosphoric that are used in conventional coolants.
The use of organic acids in engine coolants goes back to the early 1950’s when benzoic acid was used in hybrid type coolants in Europe. Coolants are classified as “conventional”, “hybrid”, or OAT based largely on how much organic acid is used in the coolant additive package.
NOTE: Some OAT coolants do not contain nitrites and molybdates, therefore, they do not have SCA units. These OAT coolants use organic acids to protect against liner pitting.
DCA-4 versus Fleetcool (DCA-2)
DCA4, DCA-4 Plus & ES™ Liquid Extenders, as well as ES™ Compleat are all based on a phosphate/molybdate/nitrite additive package. These chemicals, along with other additives, provide protection to cooling system components. Many other SCAs or Extenders such as Fleetcool (DCA-2) have a borate-nitrite base and higher levels of silicate. The liner pitting protection of DCA-4 and Fleetcool (DCA-2) is equivalent, however DCA-4 provides the following advantages:
If the pitting protection performance of DCA4 and DCA2 (Fleetcool™) are equivalent, then why is DCA4 a preferred chemistry?
How do SCAs/Extended Service Additives protect liners and blocks from pitting damage?
Attachment 2 – Cummins Inc. Coolant and Filter Specification
Cummins Inc. Coolant Specification
Cummins Engineering Standard 14603 requires that the antifreeze/coolant meet all requirements of ASTM D6210 for glycol coolant. In addition, it must:
For an antifreeze/coolant to be registered as meeting Cummins Engineering Standard 14603, the antifreeze/coolant supplier must have valid test results from competent, independent testing labs as proof of meeting the above specifications.
Cummins Inc. Coolant Filter Specification
Beginning in January 2013, all Light Duty, Midrange, and Heavy Duty engines are extended life OAT coolant compatible, and as a result the coolant filter is optional. Most Cummins® product built prior to January 1, 2013 were manufactured with a coolant filter head, and use of a coolant filter is recommended. Cummins Engineering Standard 14315 is the Cummins Engineering Standard that covers coolant filter performance. The standard contains the tests required to meet Cummins Inc. performance requirements along with the performance limits for those tests. The tests required in this standard cover the following:
Attachment 3 – Example of a Monitor C Report
NOTE: Monitor C™ Tests are not sufficient to evaluate coolant recycling processes
Recommendations: SCA is underconcentrated. Glycol concentration is excessively above recommended range for antifreeze. Use 40 to 60 percent. If system is overheating, drain and flush with heavy-duty cleaner. Fill with fresh 50/50 antifreeze/water mixture. Contact Fleetguard® for proper SCA dosage. precharge system at 1.5 units SCA per gallon, and install a service filter. See “Coolant Analysis with Maintenance Recommendations” in this section.
I have personally reviewed the data and recommendations for your sample.
Attachment 4 – Explanation of Coolant Analysis and Maintenance Recommendations (Monitor C™)
For additional information, call Fleetguard® Service Engineering at 800-223-4583 and follow the menu to get to Technical Assistance.
Last Modified: 16-May-2017