The benefits of extended-life coolants (ELC) with organic acid technology (OAT) additive chemistry are many. However, in order to receive those benefits, your fleet must properly maintain the cooling system. Proper maintenance is not exclusive to the shop technicians. Drivers must also understand the impact of their actions, especially when it comes to topping-off.

Benefits
Among the benefits of using ELC is the fact that you can improve the engine's heat transfer rate by 12 to 13 percent over conventional silicated coolants (ELCs do not use inorganic silicates). Over time, conventional coolants with silicates for aluminum protection will build up scale or deposits. Some of that is from the silicate additives or poor-quality water. As these deposits accumulate and build up thicker walls, they reduce heat transfer where it is needed most, in the hottest parts of the engine.

Another benefit seen with ELC is extended water pump life over conventional coolants with silicates. The silicates are abrasive and cause wear to the front seals of the water pump. With ELCs, water pump life may be extended up to four times. That is the fundamental difference between how conventional coolants protect the metals and how OAT protects the metals.

Conventional Coolants
With conventional formulas, the inorganic additives lay down a protective layer, coating all of the metal surfaces with an impenetrable barrier, keeping the liquid away from the metals. This works well, but because of flow and erosion, the protective layers are eventually removed. Depending on the model engine you are running, higher operating temperatures in recent years have also contributed to more rapid depletion of conventional additives. This necessitates adding a charge of supplemental coolant additive (SCAs) to replenish the additives and reinforce the protective layers.

OAT Additives
OAT additives work differently. They protect only the area of the metals surface where corrosion is imminent. This is done at the molecular level. One of the reasons that OAT has extended life is because only small amounts of the additives are utilized at a given time. One of the worst things that can happen to fleets that rely on ELC is that the driver tops-off with another coolant and nobody else recognizes this mistake until there is a severe liner pitting and a $10,000 overhaul.

ELC manufacturers pretty much agree that adding small amounts of conventional coolant or water to ELC will not harm the system. However, if you exceed 20 to 25 percent of the total fluid volume, then you may get into trouble. For example, if you have a 12-gallon system and you add three gallons of conventional coolant, you are at the maximum safe limit. A typical over-the-road engine will require eight gallons of additional fluid to top-off per year.

If you are topping-off with good water, then you may be able to drain off some of the coolant and add new product to bring it up to the correct ratio. If you are adding conventional coolant to your ELC, you must either drain and flush the engine and add a fresh charge of ELC pre-mix, or maintain the system as conventional and add SCAs as needed.

The dilution or contamination from not using the same ELC as top-off will not only cost you additional money, but you'll lose all the benefits of using ELC.

Coolant Check
So how do you check your coolant to ensure it is being maintained correctly? Until recently, a common test method involved a two-step paper test strip that is supposed to determine if your OAT additives are still at an effective level. Some manufacturers say that they don't actually measure the organic inhibitors. Some complain that the two-step procedure is too difficult. Also, different OAT formulas do not react the same way. The only sure method of testing your ELC is to send it to a laboratory for a liquid chromatography test to determine the actual concentration of the organic acids in your coolant.

According to TMC RP 1416, the appropriate laboratory test for carboxylate additives (OAT) is through the test method using high-pressure liquid chromatography (HPLC). Most labs offering to test OAT additives use the same field-test strips you have in your shop, and they are only slightly more reliable in the lab than in your shop. Recently, Staveley Services developed a new approach to traditional HPLC testing, and has been able to make it a more affordable test.

This test for ELC organic additives is offered at two levels. One level provides the cumulative concentration of the organic acids in percent. A higher level of testing provides the specific organic acids and percent concentrations of each one. Staveley can also let you know if you still have sufficient additive levels for continued use, or if you need to take corrective action. Both levels of tests are affordable.

The coolant testing is bench testing for OAT ELC. If you want to be sure of what's in your ELC, choose this test. This testing is performed with liquid chromatography, not the field strip tests.

Strip tests are available, but the new advanced technology is recommended. Why risk your engines on a $1 field test when you have an analytical lab at your service? The job of the laboratory is to let you know if you have a drop in inhibitor additives and to identify the source of the problem: excess water dilution, conventional coolant contamination or extended service.

Choose this test package to determine what's really in the radiator.

About the Author

Jonathan Sowers is the marketing manager of technical services for Staveley Services Fluids Analysis, a provider of comprehensive oil, fuel, coolant and metalworking analytical services. For more information, visit www.staveleyna.com.