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Almost all auto makers and many heavy equipment manufacturers now factory fill their new machines with extended life coolants (ELCs). While these coolants are more expensive than traditional coolants, their advantages are too good to ignore.
The additives in traditional coolants plate out over time on the inside of your radiators’ surfaces, creating a mineral coating that reduces the efficiency of heat transfer. And once the traditional additives are used up, typically in 20,000 or 30,000 miles, you have to flush and fill with new coolant or put in new supplemental coolant additives (SCAs).
The additives in the new organic acid technology (OAT) ELCs only attach to the interior surfaces at the point of corrosion. So you don’t get the heat trapping layer of additive blanketing the entire system. As a result, your engines run cooler, reduced solids in the coolant extend water pump life, and the additives deplete hardly at all.
Coolant specs vary, but even in the low range many ELC/OAT coolants are rated to last up to 750,000 miles on heavy trucks and 6,000 hours on off-road equipment. Some boast numbers as high as a million miles on trucks and 15,000 hours on off-road equipment.
Fill it and forget it?
So does this mean your new OAT coolants are maintenance free, “fill it and forget” products?
“Absolutely not,” says Jeff Snyder, industrial brand specialist for Chevron. “That’s the biggest mistake I see. If something goes wrong with your cooling system and you’re not paying attention, it could become costly.” You don’t have to worry about the coolant, but rather keep an eye out for any mechanical failures in the cooling system or accidental contamination of the coolant, he says.
“People will contaminate a system sometimes, and you can catch that by just looking at the color of the coolant and checking to see if anything is floating around in it,” Snyder says. “If there is a head gasket issue, you might get oil in the coolant. If your coolant is brown, that might indicate rust or corrosion.
There’s a lot you can do with your regular senses – sight and smell.”
Freeze point checks
The only routine maintenance you need to perform on your ELCs is to check the freeze point, which will tell you the concentration of the coolant – typically 50/50 coolant to water, but sometimes 60/40 is used in extremely cold weather.
“We recommend checking the freeze point using a refractometer,” says Stede Granger, OEM technical manager for Shell Lubricants.
Check it every time you change the oil, Granger says, but also recheck it anytime there is a change – if coolant is lost during a maintenance procedure or a driver or operator tops up the radiator. “If you get too much water you start to lose protection and a cylinder liner can pit fairly quickly. If you get it too concentrated you start to lose some of your heat transfer properties,” he says.
The best advice for topping up is “top off like with like,” says Cook.
Getting a perfect 50/50 mix after a top off can be tricky, especially on large machines with big cooling systems. Granger recommends doing a freeze point check before the top off, especially if the low levels are a result of evaporative loss. “You may want to put a gallon of water in there instead of a gallon of 50/50,” he says. “We have a chart that enables you to look up the freeze point and the amount of coolant in the system and then see exactly how much water and how much coolant to put back in,” he says.
The scale on the chart stops at 60 percent, Granger says, but there’s a trick you can use on overly concentrated coolant. Take a sample of the coolant and mix it with an equal size sample of water and take a new freeze point check on that. It will put you back into a scale that allows you to read the freeze point on the chart.
When mixing a concentrated coolant of any type, manufacturers recommend using distilled or de-ionized water, or the purest water you can get.
“Hard water, well water and even city water has magnesium or calcium particulate in it,” says Snyder, “which can plate out through your system and reduce heat transfer capabilities. This scale can also break off and damage the water pump or seals. Scale could also eventually plug a heat exchanger and give you inefficient operation or prevent heat from flowing into the cab in wintertime.”
Additionally, city water has chlorine and fluorine in it, which can form acidic compounds that over a long period of time will shorten the life of the cooling system.
Obtaining large quantities of distilled or de-ionized water can be a logistical challenge. Managers of larger fleets sometimes install their own de-ionizing equipment, but you can also buy purified water in bulk totes from local vendors or in a pinch grab some at the grocery store.
Even though distilled or de-ionized water is recommended, OAT coolants are more tolerant of readily available sources of water like tap water, says Gapinski. “If you get some iron in your system the phosphates and silicates in traditional coolants could form insoluble precipitate that deposits on the radiator and other parts of cooling system, whereas the OAT chemicals don’t do this so you are less likely to get precipitates or scale.”
If you don’t have access to de-ionized or distilled water Gapinski recommends using a 50/50 prediluted antifreeze.
Mixing different coolants
Another practical concern is that drivers or operators away from the shop or a knowledgeable service tech may mistakenly put in a traditional coolant to top off a system that’s running on OAT coolants. That’s not good, but it’s not fatal either. The chemical formulations don’t fight each other, but neither do they help each other.
“Compatibility generally isn’t an issue,” Cook says. But if you run a mixture of coolant types you may void the extended life warranty and will likely not reap the full benefits of the ELC,” he says.
“The rule of thumb is if you contaminate either product by more than 20 percent then you have to take corrective actions to fix it,” Snyder says. “If you mix the two beyond that then there generally is not enough of the additives of either type to protect the system.”
Testing and sampling
When you buy a used truck or machine it can be difficult to determine what kind of coolant it has. There are color standards, but not all companies follow them.
You can pull a sample and send it to a lab for confirmation. Or, flushing and filling is also an option, although expensive if you’re dealing with a large cooling system. Many of the coolant manufacturers offer test strips and sample packages that can also aid in identifying the type of coolant you had.
You should also test ELCs at the intervals recommended by the coolant company or equipment manufacturer for the presence of organic inhibitors and for wear metals and contaminants. You may only need to do this once a year or so. In most cases the coolant will be fine, but regular testing can also alert you to mechanical or other problems in the system.
Nitrites or not
There’s a healthy debate over the suitability of ELC formulas with nitrites in them.
“There are some people who think that nitrites are necessary to prevent cylinder liner cavitation, but there is a lot of data to show that this is not true,” says Gapinski. “Modern OAT coolants without nitrite have an inhibitor system that is more than adequate. But some of those traditions die hard.”
In some Asian countries, environmental rules prohibit the use of nitrites, and there are some in the industry who are concerned about the affect of nitrites on aluminum in the cooling system.
“I think the industry is moving in the direction of non-nitrited coolants,” Cook says. “As the cooling systems become higher in aluminum content and the flow rates get faster in the, the nitrites in ELC coolants get exposed to more aluminum. This can raise the pH of the coolant and cause some issues.”
As a general rule, Japanese engine makers like Komatsu and Isuzu favor non-nitrited coolants and Cummins and Navistar have recently come out with nitrite-free specs for some of their newer engines.
Most coolant companies offer nitrite-free formulations to meet these needs. Be sure to check with your truck or equipment dealer and your coolant supplier to determine the best product to use.
OAT coolants have been around since the 1990s, but it took a while for them to catch on, says Rich Gapinski, driveline and ancillary senior technologist for Castrol. “It wasn’t until well into the 2000s that they became more widely adopted,” he says. Caterpillar was the front runner in embracing the OAT coolants, and now nearly all OEMs and truck manufacturers have followed suit, he says.
“The old technology is still out there, and one of the reasons is price, “Gapinski says. “Traditional heavy duty coolants are cheaper in the short run. But if you do the math and consider the benefits, the more expensive initial price of the OAT coolants far outweighs what you’re going to get in a traditional coolant.”
The automotive world switched to ELCs 12 or 13 years ago,” says Frank Cook, senior vice president and technical director at Old World Industries. “Almost every car in the world is factory filled with OAT coolant of one sort or another. Every area of the world has its bias. The Japanese don’t like silicated coolants and they like phosphate in their coolants. The Europeans forbid phosphate in their coolants. But they’re still all basically OAT.”
The heavy-duty diesel world is catching up, Cook says, and he estimates that OATs have about 40 percent market share. One reason they haven’t completely taken over the market yet is that some maintenance practices just die hard. For decades fleet managers closely monitored SCA levels to prevent wet sleeve cylinder liner cavitation. OATs are just as good at preventing cavitation, but the practice is hard to change.
Mix coolant with any old water? Think again
Hard water, well water and even city water has magnesium or calcium particulate in it. This can plate out through your system and reduce heat transfer capabilities. The resulting scale can:
• break off and damage the water pumps or seals
• plug a heat exchanger
• prevent heat from flowing into the cab.
The Waterless Difference
Originally formulated to alievate hot spots and early detonation in high performance race cars, Evans Waterless Engine Coolant is finding increasing relevance for today’s hotter running, heavy-duty diesel engines, says,” says Mike Tourville, director of marketing.
In normal operating range, water-based coolants run at 180 to 185 degrees Fahrenheit. Add 20 degrees and you come close to water’s boiling point. If temperatures stray beyond the boiling point of water, vapor pockets form inside the system and you lose most of the coolant’s thermal conductivity in those areas. These hot spots may cause in-cylinder fuel to ignite prematurely. And pressurized cooling systems can force those vapor pockets to remain in one place causing engine damage.
With a boiling point of 375 degrees, Evans Waterless Coolant gives you a greater thermal margin and protection from this kind of damage. And since it has no water, it can’t cause corrosion within the radiator, pumps or cooling system. It requires less pressure, 3 or 4 psi, vs. 15 psi for a waterbased product, so you have less stress on the sytem and less liklihood of leaks, Tourville says.
Fuel savings come from having the ability to set your fan-on temperature higher. “If your cooling fan is programmed to come on at 210 degrees, we can elevate that to 230 degrees,” Tourville says. And since the fan draws considerable horsepower, less frequent use of the fan brings fuel economy advantages.
Water, however, is cheap and plentiful, and the price difference for Evans Waterless Coolant is $47.95 a gallon, vs. about $14 for conventional coolant. “But if you save 3 percent in fuel economy it will pay for itself in as little as three months. You also reduce corrosion and cylinder liner cavitation, you don’t need to add SCAs or top off evaporative losses, and it is an extended life coolant so you eliminate replacement and disposal as well,” Tourville says.