Coolants Require Check-Ups to Maximize Engine Life

This story appears in the July 28 print edition of Transport Topics.

Although some fleets and truck makers are turning to extended-life coolants because they are said to lower engine heat and maintenance costs, they still require regular checkups just as conventional coolants do, suppliers said.

The most important thing, they said, is to check and test any type of coolant regularly and to adhere to manufacturers’ recommended maintenance schedules.

There are two types of coolants used in heavy-duty trucks: fully formulated coolants, which have the same core chemistry as a conventional coolant but have additional inhibitors, known as supplemental coolant additives or SCAs; and extended-life coolants, which have inhibitors that last longer than fully formulated coolants.

Fully formulated and extended-life coolants use ethylene glycol for boil-over and freeze protection.

“ELC does a better job of removing heat because of added heat-transfer capabilities,” said Jeff Snyder, industrial brand specialist for Chevron Products Co. “Conventional coolant creates a blanket of protection throughout the system. If you remove a hose, you will see a thin layer of inhibitors throughout the inside.” ELCs only get closer to the metals they are designed to cool, he added.

The bottom line is, because supplemental coolant additives are added more frequently with conventional coolants, maintenance costs are higher than they are for ELC users.

Colin Dilley, vice president of technology for Prestone Products Corp., said, “Conventional coolant provides adequate protection; however, with shorter coolant life, it can lead to more maintenance.”

Joe Long, director of fleet sales for Peak Commercial and Industrial, said, “Many fleets utilize . . . ELC coolants due to less maintenance cost as compared to conventional or fully formulated coolants.”

He said that one form of ELC is popular with the OEMs.

“ELC coolant inhibitor packages are known as organic acid technology. Most factory fills today are with an ELC that is a NOAT [nitrited organic acid technology] type of coolant,” he said. “This gives you protection from the OAT inhibitors and additional backup protection because of the addition of nitrites.”

Steve Muth, chief chemist for Penray Cos., said, “The key to maintaining any cooling system, conventional coolants or ELC, is sampling the coolant and testing it as part of a regularly scheduled program.

“While some problems may be easily identified visually, such as contamination, lab testing [provides] for more in-depth evaluation.”

Penray makes cooling system products and fuel and oil additives.

Muth said testing methods — some of which can be conducted by fleets — include liquid test kits and hydrometers, instruments used to measure the relative density of liquids.

“We have dedicated training programs that are specific to the heavy-duty market covering cooling-system chemistry, the role of specific chemical components, service scheduling and, of course, the role and value of periodic testing,” he said.

Dan Arcy, OEM technical manager for Shell Lubricants, said in a statement, “The most important thing to know is the type of coolant you have in your truck and to not mix coolant types. Each type of coolant is different and needs to be maintained in a different way. This is particularly important for both conventional fully formulated and ELCs, which can be contaminated if they are diluted with other types of coolants.”

Arcy also said, “The Technology and Maintenance Council of the American Trucking Associations has established recommended coolant colors for different types of coolants. The colors are not required, and not all manufacturers follow the recommendations.

The recommended colors:

• Red for extended-life coolants

• Purple/pink for fully formulated ethylene glycol-based coolants

• Blue for fully formulated propylene glycol-based coolant

• Green for conventional coolant

Tracey Meyer, product marketing manager for HVAC and expendables at Daimler Trucks North America, said, “In general, technicians should check coolant on a routine maintenance schedule. The five basic tests for all coolants include: color, clarity, odor, freeze point [percentage of glycol] and chemical protection.”

Chevron’s Snyder also said despite the type of coolant, “The basics of maintenance remain the same: regular testing, checking, topping up and flushing.”

He stressed the importance of the simple, everyday checks of the system because “40% of all engine failures are coolant-related.”

Snyder added that means fleets need to be certain the system is full of coolant. “A leak and low volume of coolant can oxidize your oil. This can shorten the life of your oil and increase wear rates.

“Make sure the coolant is clean, and looks clear. There must be no oil floating, and no fuel smell. [And] make sure the color is correct: red for ELC, and purple, green or brown for standard antifreezes, depending on the exact type.

“This takes only 30 seconds,” he added. “Look at the overflow tank, and you could catch a major mechanical issue — for example, a failed head gasket, which means exhaust is getting into the coolant. This will change the PH. A one-point drop has serious consequences.”

Snyder said it is important to maintain freeze-boil and corrosion protections, which for those using standard coolants means maintaining the right level of supplemental coolant additives. While the additives are designed to minimize these problems, those who use conventional coolants should remember that an excess of SCAs reduces heat transfer well below the level of which the coolant should be maintained. “Maintenance intervals should be set by the vehicle manufacturer, and diligent coolant testing should be adhered to. This will ensure that the coolant is always protecting the engine,” Prestone’s Dilley said.

“Periodic maintenance and testing is required for conventional and fully formulated coolants.” Fully formulated coolants have an initial charge of SCAs blended in, Daimler’s Meyer said.

“The inhibitors used in fully formulated [conventional] coolants work extremely well but deplete faster [than ELCs] over a short period of time. Systems using fully formulated coolants should be tested at least every 90 days/25,000 miles or 800 hours,” he said.

“Both conventional and fully formulated coolants require periodic-maintenance and testing,” Peak’s Long said. He agreed with Meyer on how frequently these products should be tested and how.

“Chevron recommends flushing out conventional coolant after 10 doses of SCAs [because] the fluid accumulates too many solids. It should be drained and refilled after 200,000 to 250,000 miles,” Snyder said.

“Our ELC is good for 750,000 miles, or 1 million miles if, at 500,000 miles or four years, you put in Delo Extender. Routine checking of both products is needed. SCAs in conventional coolants should be replaced every 15,000-25,000 miles. You can correlate with oil changes,” Snyder said.

“As a guide, our ELC is a 600,000-mile coolant that requires an extender at 300,000 miles. [Prestone] Command extended-life technology follows TMC guidelines, and SCA should be added as required, which again requires diligent testing.” Dilley said.

“With ELC, we recommend checking the freeze point twice a year, and additive chemistry once a year. You can send a sample to a lab, or quickly check it with a field-test kit in the shop,” Snyder said. “If someone dilutes ELC, you can top off the radiator with anything and then correct it when you get back to your shop. The easiest thing to do is to drain and refill.”

Truck makers generally agreed with coolant providers. However, Kenworth Truck Co., a Paccar subsidiary along with Peterbilt Motors Co., said fully formulated coolants must be changed every 200,000 to 300,000 miles or two to three years, with periodic testing and addition of SCAs between changes. And Volvo Trucks, which along with Mack Trucks is owned by Sweden-based Volvo Group, said it has a Quick Care Fluid Analysis Program designed to monitor and evaluate the coolant’s performance. The OEM also can provide fleets with test kits that can help identify contamination in the system — which can cause corrosion, pitting, water pump failure and shorten the life of the vehicle.

Cummins Inc., Safety-Kleen Systems, ExxonMobil and International Truck & Engine Co., owned by Navistar International Corp., did not respond to requests for comment.