Keeping Cool

Cooling system recommendations simplified.

From water quality to coolant choices to owning a mixed fleet of light duty vehicles, recommended maintenance tips are as simple as they seem. "You are talking about gas or small diesel solid block engines. Those vehicles will come with recommendations in the owner manuals that include what kind of coolant to use and when to change it out," says Frank Cook, Ph.D., senior vice president for Old World Industries, Inc. "It boils down to following the vehicle manufacturer's recommendations."


When selecting a coolant to use in your vehicle, "The world breaks down into two different kinds of coolant: conventional, inorganic inhibitor systems which will last two or three years before they have to be changed out; or extended life coolants which last 100,000 to 150,000 miles before they have to be changed out," says Cook.

According to Jim Roberts, technical service specialist for Shell Lubricants, "In light duty, there is a real fragmentation between Ford and Chrysler vs. General Motors (GM).

"Ford and Chrysler have their coolant, which is a hybrid coolant that uses nitrite and silicate. They don't recommend DEX- COOL™ and GM doesn't recommend the hybrid," he says. "It is very difficult for a mixed fleet to meet the specific requirements of the different OEMs--there is no one coolant that is recommended by all the automotive companies."

Roberts cautions maintenance managers that just because the coolant in your vehicles is one color, don't automatically assume that the orange coolant you buy is the same coolant specified by the manufacturer.

"Fleets either buy the different types of coolants recommended by the OEM or they will just not worry that much about the warranty period and go to one coolant--which could potentially cause problems," he says. "One problem can lead to many problems."


"Does the coolant cause corrosion, overheating, sludge or does it eat away at the gaskets? My answer would be no. The coolant is not doing that," says Roberts.

"Being a coolant supplier, we work cloesely with equipment manufacturers to provide coolants meeting their specifications. They know that the coolants that are provided work in their equipment. If you have a cooling system issue, it isn't necesssarily a coolant failure.

"Coolant just doesn't quit working unless perhaps it has gone beyond its coolant lifespan. If you are talking about issues that happen in the system, they are generally either maintenance related or mechanically related," he says.

Roberts points out these key issues to watch for:

  • Low coolant levels--if the coolant levels aren't maintained you may get aeration, corrosion and then the corrosive metals can disperse throughout the system and plug up the radiator or the heater core.
  • A bad radiator cap is another problem. If your radiator cap isn't holding pressure you will lose coolant, your coolant will boil over or you can have aeration as well.
  • A big problem is coolant that is over- or under-concentrated. If you are finding that the coolant level is always low and you are constantly putting in straight antifreeze or straight water, then you are losing either freeze protection or heat transfer or even corrosion inhibitors.

Roberts wants maintenance managers to understand that cooling system problems or component failures aren't necessarily their fault.

"Situations where people complain that their coolant is eating their gasket or issues like that--those aren't normal issues. These issues are usually anomalies due to some kind of cooling system design failure or function.

"Manufacturers test and approve the coolants, but there are real world situations that take the cooling system and coolant out of the range in which it was evaluated," he says. "That's when things can start going wrong; if the design has changed or if the cooling system is faulty, it's something that happens to make the coolant no longer able to function."


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