Light Duty: Color By Numbers

Here's how to avoid "Coolant Confusion" in your shop.

“The problem with antifreeze/coolant,” Justice goes on, “is that you don’t really do anything to lower the temperature; all it does is stop it from boiling. It’s a better antifreeze than it is a coolant. It’s basically ethylene glycol; that’s the same thing they use to de-ice airplanes in the winter. So, it’s the best thing out there as an antifreeze, but as a coolant, it’s not that good. The simple fact that your coolant isn’t boiling over doesn’t mean that it’s any good.”


There may not be any totally foolproof method to insure that technicians are using the right coolant (and using it properly), but Shell’s Alverson offers some “obvious steps” that fleet maintenance managers can take:

  • Training and requiring the technicians to consult the OEM’s manual recommendations when in doubt;
  • Placing stickers on the radiator overflow tanks specifying the correct coolant for each vehicle in the fleet;
  • Stocking the OEM recommended coolant for each vehicle;
  • Sign-up on the work order on the type of coolant filed in to the vehicle.

“By no means should color be used as the sole indicator for the type of coolant to use,” Alverson says. “The hybrid coolants can come in red, yellow, violet, orange, blue, according to the OEM or the coolant supplier recommendations. Only on the heavy-duty side are there recommended color standards for various types of coolant.”

Still, questions remain, according to Brad Drake. “The most common question comes when it’s time to service the coolant system on a vehicle that’s been around a number of years, and the fleet manager wants to know if they have to stick with the same coolant that the vehicle came with (they don’t),” he says.

“Another common question is ‘What can I top off with?’ It can be hard to identify the coolant in the system if you didn’t put it there,” he says. “Color can tell you some things, but whan the color can’t tell you is whether the coolant employs organic or inorganic acid technology.

“Usually what will happen is, if you somehow mix organic and inorganic acids, they’ll neutralize each other and you’ll lose some of the benefits,” he explains.

Rather than take the risk of topping off a coolant system with the wrong product, Drake advises technicians to drain and flush the system completely and start from scratch.

“It’s an unappetizing suggestion, but it’s really the safest thing to do,” he says.


No matter what coolant you use in your fleet vehicles, Shell’s Alverson suggests that you monitor its quality and effectiveness with a coolant analysis program: “If you couple your coolant program with coolant analysis, you can extend your drain intervals.

“We recommend a periodic coolant monitoring program that looks at coolant concentration, the PH level, the corrosion inhibitor level (organic and inorganic), corrosion metals, coolant degradation, oxydation products, and contimination,” he says. “Pick out a few vehicles, do the used coolant testing at various mileage intervals, and see if you can’t extend the coolant drain interval.”

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