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Cooling system care

Know when the coolant needs to be replaced, and why.
Friday, August 31, 2012 - 11:38
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Why is it that our heavy-duty cousins can get so much more life out of their coolant fills than we can? It’s not unusual for a Class 8 rig to go as far as 600,000 miles before needing a complete coolant replacement. Yet OEM maintenance intervals for most cars and light trucks (using extended life coolants) top out at around 150,000 miles. And I’d be willing to bet that many shops are recommending coolant replacement every two years or 30,000 miles, regardless of the type of coolant in use.


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How is cooling system service performed in your shop? Is it a service recommended off of the menu, based on mileage? Or is it a service recommended based on need?

How do you perform that service? Do you still offer “drain and fill” as an option or do you perform a thorough cleaning, followed by a flush and complete refill?

Here are a few ideas on how to offer a professional cooling system service to your customers.

Coolant Formulations
The cooling system, and the coolant in it, has some pretty important tasks to perform. The cooling system is fundamental in maintaining the engine’s operating temperature in a specified range. The coolant is the means to transfer that heat from the engine to the radiator, where it can be released to the outside air. And while water alone is a great medium, we all know coolant uses a glycol base to prevent the water from freezing up on those cold winter nights.

To this point, coolant brands are nearly identical. What differentiates the variety of coolants on parts store shelves is the formulation of the inhibitors they use. Inhibitors are the chemical additives that help prevent corrosion and erosion damage in the internal passages and components of the cooling system. Dyes also are added to today’s coolant formulations. A word of caution here: Don’t rely on coolant color as a way to tell if a customer’s car has the right coolant installed. Dye color is a matter of OEM or aftermarket choice, and has no relationship to the formulation of the inhibitor package.

Conventional coolants for domestic makes are typically green in color, and use a phosphate/silicate inhibitor package. Problems with the water sources in other parts of the world necessitated slightly different inhibitor formulations. All conventional coolants rely on inorganic inhibitors to protect the internal system passages and cooling system components. These additives work by forming a protective blanket that actually insulates the metals from the coolant. But this also depletes the inhibitor package in a relatively short period of time, requiring replacement every two years to insure the inhibitor package is able to do its job.

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