They could have picked more manly colors. I mean, we’re talking about real men who drive big trucks pouring little jugs of pink liquid into their big beefy engines… Honestly. The colors are actually a product of the chemical content of the coolant, and they help identify what type of antifreeze is in your engine.
There are clues in the colors, but that’s not the end of it. Two types of antifreeze are available today: conventional (including fully formulated antifreeze) and the extended-service (ESL) blends. There’s a third type easing its way into the market now as well, called ‘fill-for-life’, a combination of the other two.
The conventional coolants tend to be green, or maybe blue, while the extended-service products are usually red or orange. There’s some pink out there as well, but more than a few radiators are likely full of something muddy brown in color. That’s because somebody mixed two types of
The green stuff is the so-called low-silicate, phosphate-free antifreeze containing a blend of inhibitors and additives, such as silicate, nitrate, borate, phosphate, and molybdate. It’s been around for years and it works really well, but requires a fair degree of hands-on maintenance.
There’s frequent but inexpensive testing involved, and regular recharges of inhibitor chemical must be added periodically to bring the chemistry back up to scratch.
The upside to conventional antifreeze is that it’s very tolerant of mixing and dilution. The active chemical base can easily be restored with the addition of the appropriate additives. The downside is the effort involved in testing and maintaining the product. If it’s neglected, depletion of the active chemicals such as the nitrite cavitation inhibitor can quickly cause internal problems.
“I’ve seen engines – two right here in town in the same month – with less than 150,000 miles on them that had holes chewed right through the side of the block,” says Dominic Zappavigna of Waterous Detroit Diesel in Calgary. “Both engines had the proper antifreeze, but the owner hadn’t bothered to replenish the additives or inhibitors.”
The red and orange antifreezes, the ESL products, have a different chemical makeup entirely from the conventional products. They still use either ethylene glycol or propylene glycol as their base, but they rely on nitrite organic acid technology (NOAT) to provide the protection. NOAT, which contains anti-corrosion compounds like aliphatic mono- and di-carboxylic acids along with tolytriazole and nitrites, is common to most ESL coolants.
Zappavigna says it’s becoming harder to make an informed decision about antifreeze with so many different types of product on the market. He stresses that all the major brands and types of antifreeze perform well when used in accordance with the manufacturer’s instructions. It would be hard to say one formulation is quantifiably better than another. The choice of antifreeze is often based mostly on maintenance considerations, such as the time and money involved in servicing the stuff and the availability of a retail source of the product. Simply put: you now have a choice of two different types of antifreeze each designed to do the same job, but in a slightly different way.
You may not be aware, but you can spec your coolant when you buy a new truck. All the OEMs have supply agreements with the major coolant suppliers, so you’ve got some flexibility in what you can put into your radiator. You’ll likely get the house brand, but you can choose between
conventional and ESL antifreeze.
The appeal to the ESL coolant is that it’s designed to be left alone. As a rule, you don’t need to replenish the inhibitor stock and it requires little in the way of maintenance. Typically, you’ll have to add an extender to the product somewhere around the 300,000-mile mark, and it’s possible to go out beyond 600,000 miles if the antifreeze continues to test to acceptable limits. Some newer products go even further on both counts.
All brands of ESL antifreeze require periodic testing, but do-it-yourself test kits are not yet available. Testing requires sampling and the samples must be sent to a lab for analysis. At $10 to $20 a pop, several times a year, that gets expensive. But that’s the price you pay for less
labor-intensive cooling system maintenance. Most of these ESL coolants also use a water filter loaded with time-release pellets to maintain the inhibitor charge throughout the life of the filter.
Some brands of ESL antifreeze will tolerate minor cross-brand contamination, but none of them take well to contamination with conventional coolant or dilution with excessively hard water. If the coolant becomes sufficiently contaminated, you’ll have to flush everything down the drain and refill the system with fresh product. If that seems like a steep price to pay, it is, especially for an owner-operator who may not be able to find a supply of ESL antifreeze on the truckstop shelf when he needs a gallon of make-up coolant.
According to Jay Johnson of The Penray Companies, a major supplier of OEM-branded antifreeze, the major drawback to using ESL coolants in a long-haul operation is the possibility of contamination.
“You might not be able to get your hands on the proper make-up antifreeze when you need it,” he says. “There’s a limit to how many extra jugs you can carry around with you, and there’s always the possibility that someone will add the wrong product to the system during routine maintenance.”
For a fleet whose trucks never stray too far from home, and who can stock an adequate supply of coolant in the garage, the ESL can be a real time-saver. For the highly mobile owner-op, it might be best to stick with the readily available traditional coolants for a little while yet.
If you’re running any brand of conventional fully-formulated antifreeze, the manufacturer’s guidelines will recommend periodic testing of the coolant. All that’s required is dipping a test strip into the coolant and comparing it to a graded color scale on the side of the bottle. The kits are an inexpensive and effective means of measuring inhibitor concentrations.
Conventional coolants can also be used in most cases with a time- or need-release water filter containing measured applications of nitrite and SCA. These filters render the conventional coolant as close to hands-off as it’s likely to get, but periodic testing is still advisable.
The good thing about conventional antifreeze is that a minimum amount of testing will still provide a fair degree of assurance that your coolant is up to snuff. At the very least, conventional coolants should be tested for nitrite concentration at every scheduled service interval and nitrite make-up product can be added as it’s needed.
It’s important to use a test kit that’s approved for use with your brand of antifreeze. Blends of various brands of antifreeze can skew the test results, and some test kits are incompatible with other brands. It’s best to use the same brand of antifreeze, SCA, and test kit at all times.
Conventional antifreezes may require a substantial amount of attention, but they’re durable and flexible enough to withstand dilution from incompatible antifreeze or higher concentrations of straight water. So pick your favorite color, but don’t base your call on what will look best in a
puddle under the truck.
Pitting is one of the most common and costly results of improper cooling system maintenance. Pitting, left unchecked, eventually leads to perforated cylinder liners.
As combustion occurs, the liner vibrates within the block. The outside walls of the liner actually move away from the coolant causing a near vacuum for an instant (this process is called cavitation). The vacuum-induced low-pressure area causes the surrounding coolant to boil, forming tiny bubbles. The liner then returns to its normal position, compressing the bubbles violently and causing them to implode against the liner wall at pressures up to 60,000 psi! The collapse of these bubbles actually blasts small holes in the iron, eventually boring through the liner and allowing coolant pass into the combustion chamber.
To prevent cavitation, antifreeze blends contain chemicals which form a thin protective film on the coolant side of the liner wall. This film acts as a barrier to prevent corrosion, cavitation, and pitting.