Kings of Cool

| April 07, 2005

A jug of the Texaco Extended Life Coolant, also marketed by Caterpillar and Shell. It uses carboxylates to give stable, long-term protection, but must always be replaced with the identical formula or protection will be lost.

Do the Coolant Two-Step
Know how to choose the right blend and then keep it working for you

You have two choices when it comes to easy-to-maintain systems for heavy truck coolant.
The first option is to use only fully-formulated coolant, a blend that protects the system right out of the bottle, together with a “need-release” filter supplying supplemental coolant additives (mostly nitrites) as needed. You make sure the system is clean, refill with this antifreeze and then install an SCA-control filter. Controlling how the SCAs flow into the system not only saves the trucker a lot of maintenance, it prevents the SCAs from accumulating as solids in the system, which would require a coolant change much sooner.

Darrell Hicks of Penray, which makes a need-release filter, says the filter has a cake of SCAs in it that looks like “a puck of toilet bowl cleaner.” The secret to the filter’s ability to control system SCAs is a membrane that separates this “puck” from the coolant flowing through the filter. To the molecules in the cake of SCAs, the membrane is like a screen door with tiny holes in it. The membrane allows the SCAs to pass through, but only if “the relative corrosiveness of the coolant” reaches a certain level, says Hicks. As you drive and the chemical effect of the SCAs in the coolant starts to drop, that’s when the filter adds SCAs automatically. The filter also removes debris from the coolant to help keep other dissolved solids from shortening its life.

There are various brands of need-release type filters with varying change intervals, but they all last much longer than the traditional maintenance type filters. The Penray need-release unit is normally replaced at 15 months and 150,000 miles. Once the system is working, all you really have to do is make checks so you can be sure only the right coolant has been added.

Your second option is extended life coolant. One example is the ChevronTexaco/Caterpillar extended life coolant (ELC), also marketed under the Shell Rotella and DDC Power Cool Plus brands. This coolant uses carbolic acid, which breaks down much more slowly than SCAs, providing long-term protection with almost no maintenance. All you do is add a bottle of extender at 300,000 miles and then change the coolant at 600,000 with most brands of engines (check the manufacturer’s specific recommendation).

Cummins Fleetguard markets a hybrid carbolic acid coolant called ES Compleat that adds a few SCAs to the system and uses a need-release type filter to do so.

After you have chosen your coolant, the only difficult part of maintaining these systems is being sure to add only the proper coolant, either fully-formulated or ELC depending on which system you are using.

Keep the system tight and free of leaks. Key moves in this process include checking and tightening hoses or screw-type clamps or replacing band-type clamps as needed.

If you are not sure about the state of your coolant, Hicks suggests using a refractometer to check it. Refractometers generally run about $69. “These are pricey but accurate,” he says. “The reading tells you when the system has been invaded with either water or antifreeze.” How? You place some antifreeze on the refractometer’s glass, close the cover, point the glass toward a light and peer through the lens. The mix of antifreeze and water bends the light, creating a shadow that runs across a scale and reveals the exact freeze point of the mix. Since drivers typically add a little too much water or antifreeze, you’ll immediately notice a telltale change in the reading.

If you are still not certain, Hicks recommends checking antifreeze concentration and protection every time you change your oil. You can use test strips like the ones Penray supplies called “Fill for Life 2-Way.” You dip one test strip into the radiator or overflow tank for two seconds, then pull it out and watch what happens to the colors of two little pads. After 45 seconds, you compare the color of the pad near the end of the strip with a percent glycol scale and the color of the other with a nitrite percentage scale. You may have to adjust SCA level by adding small packets of the stuff.

If you’re using ELC, adding the wrong coolant will defeat the protection of the carboxylates, but you could then just add and maintain SCAs in order to avoid an immediate change of coolant. ELC, too, can be tested with special test strips for depletion of its protection.
Erickson recommends that you avoid using any kind of water filter with ELC because of the chance of installing one that adds SCAs by mistake.

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