The Color of Cool

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.

Actually, the colors are 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 extended-service (ESL) blends. There’s a third type easing its way into the market as well, called “fill-for-life,” a combination of the other two.

Conventional coolants tend to be green, or maybe blue, while extended-service products are usually red or orange. There’s some pink out there, but more than a few radiators are full of something muddy brown in color. That’s because somebody mixed two types of antifreeze together.

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. The upside to conventional antifreeze is that it’s tolerant of mixing and dilution. The active chemical base can easily be restored with the addition of 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, 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. 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. Each does the same job, but in a slightly different way.

ESL’S APPEAL

The appeal of ESL antifreeze is that you don’t need to replenish the inhibitor stock. Typically, you’ll have to add an extender to the product somewhere around the 300,000-mile mark, and it may be possible to go out beyond 600,000 miles. 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 and refill the system with fresh product-a steep price to pay, especially for an owner-operator who may not be able to find ESL antifreeze on the truck stop shelf when he needs a gallon of make-up coolant.

If your trucks don’t stray far from home, and you can stock an adequate supply of coolant in the garage, ESL antifreeze can be a time-saver. If you’re more mobile, it might be best to stick with readily available coolants for now.

All brands of ESL antifreeze require periodic testing, but do-it-yourself test kits are not yet available. You’ll have to send samples to a lab for analysis-at $10 to $20 a pop, several times a year.

CONVENTIONAL WISDOM

If you’re running any brand of conventional fully-formulated antifreeze, follow manufacturer’s guidelines for measuring inhibitor concentrations. You simply dip a test strip into the coolant and compare it to a graded color scale on the bottle.

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.U se a test kit that’s approved for use with your brand of antifreeze. Blends of various brands of antifreeze can skew the 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.