It sounds too good to be true — a coolant that lasts at least 600,000 miles in your dump truck or 6,000 hours or six years in your excavator, tractor-loader-backhoe or other earthmoving equipment. That’s up to three times the life of a conventional coolant. Yet, that’s exactly the kind of performance you can expect from extended life coolants.
So, what’s the catch? You’ll probably pay about 50 percent more for an ELC and you’ll have to add an extender at 300,000 miles, 3,000 hours, or three years. But look at what you get:
• No need to add supplemental coolant additives (SCAs).
• No need to test levels of inhibitors that protect wet-sleeve cylinder liners.
• Longer life for cooling system components.
• A single coolant that can be used in both diesel and gasoline engines.
• Less coolant to dispose of, so lower disposal costs over time.
It can all add up to significantly lower cost over the life of an ELC, and more value for your money, coolant manufacturers say. “National truck fleet managers tell us that they use ELCs because these products offer longer life, less maintenance, and lower costs than conventional coolants,” says Stede Granger, OEM technical manager for Shell.
Significant difference
Extended life coolants are similar to conventional coolants in that they contain similar amounts of water (to transfer heat) and ethylene glycol (to protect the water from freezing and boiling). Most extended life coolants are red, while conventional fully formulated coolants typically are purple. But the big difference between the two — and the reason for the much longer life of an ELC — is the corrosion inhibitor additive package that protects the cooling system.
A conventional coolant uses inorganic materials, like silicates, phosphates, and borates, which coat metal surfaces to control corrosion. Because these materials become depleted, they must be replaced from time to time. Also, they plate out or build up on the metal surfaces, where they act like an insulator, holding in heat and creating hotspots. This leads to more plating and more hotspots, which eventually prevent proper cooling of the engine and can cause failure of cooling system components.
Depletion of the additives adds to maintenance costs in another way, too. As silicate coolants become depleted, the silicates form larger, abrasive particles that can damage seals in the water pump.
The additives in an ELC, on the other hand, contain organic acids salts. They have been neutralized to form carboxylates, which are highly effective corrosion inhibitors. These inhibitors eliminate the plating and insulation problems of the inorganic additives.
“The organic additives work on a molecular level to provide an electrochemical barrier against corrosion with pinpoint accuracy,” explains Fred Alverson, a coolant researcher with Shell Global Solutions. “Only a tiny bit of additive goes to the actual spot of the metal surface that requires protection. Inorganic additives blindly coat surfaces, whether they need protection or not. Also, the organic additives are much more stable. Because they deplete so slowly, they don’t have to be replenished frequently like those in conventional coolants.”
The end result is better cooling, longer cooling system component life, and much longer coolant protection. Shell’s Rotella ELC illustrates the improvement in heat transfer properties of ELC coolants. It offers about a 10- to 20-degree F temperature reduction in laboratory dynamic heat transfer tests compared to conventional fully formulated coolant. It also provides long-term protection for all cooling system metals: aluminum, brass, cast iron, steel, solder, and copper.
That extra protection is important to equipment manufacturers as well as owners. “One major OEM switched to extended life coolant because they found improvements in water pump seal life and reduction in water pump warranty costs,” says Granger.
Making the change
If you switch from a conventional coolant to an ELC, you have two options. The simplest is to drain the conventional coolant, flush the cooling system, and refill with the ELC. Or, if your conventional coolant is still in good condition, you can minimize downtime and the cost of coolant disposal by converting that coolant to an ELC.
That requires adding a conversion fluid containing a concentrate of ELC corrosion inhibitors. For instance, one gallon of Shell Rotella ELC Conversion Fluid is added for every 12 gallons of cooling system volume. The conversion kit also includes materials for collecting and submitting a lab sample to make sure the conversion to an ELC was successful.
Extended life coolants are available with or without nitrites. Heavy-duty ELCs are traditionally formulated with nitrites (or with nitrites and molybdate) to protect engines with wet-sleeve cylinder liners from cavitation corrosion. The organic additive corrosion inhibitor technology in nitrite-free ELC coolants provides satisfactory cavitation protection without nitrite, Alverson notes. The new nitrite-free ELCs also protect today’s high-aluminum-content engines by eliminating aluminum-nitrite interactions that may occur under severe operating conditions.
Depending on the manufacturer, you can buy an ELC in a concentrated formulation where you mix in the water, or in a 50/50 mixture, where the coolant is pre-mixed with de-ionized and de-mineralized water. “We recommend using the pre-mix,” says Alverson. “That way, you’re assured that you don’t add too much or too little water or coolant to your system.”
Simple maintenance
Keeping an ELC performing properly is much easier than with a conventional coolant. Alverson stresses the importance of checking the coolant for freeze point protection twice a year. “The proper mix of water and glycol for just about anywhere in the United States is 50/50 throughout the year,” he says. “This will protect against freezing to -34 degrees F. Use this same mixture when topping off. If you just add water, you’ll have less freeze protection and reduced corrosion protection.”
In Alaska and Canada and other areas of extreme cold, glycol concentration can be increased to 60 percent to provide freeze protection down to -59 degrees F. Alverson does not recommend any higher glycol concentration.
Although the depletion rate of corrosion inhibitors in ELCs is extremely low, they do have to be replenished. So make sure you add the correct amount of extender at the midpoint of the ELC’s life: 300,000 miles, 3,000 hours, or three years.
Depending on how well you maintain your cooling system and how you operate your equipment; an ELC may still have life left in it after the first 600,000 miles or 6,000 hours of operation. So it may pay to have it tested before replacing it.
Manufacturers don’t recommend mixing ELCs and conventional coolants. “The two types are compatible in terms of mixing, but the inhibitors represent different chemistry and won’t work together,” says Granger. “You end up reducing corrosion protection of both. Also, you won’t lengthen the life of the conventional coolant, but will shorten the life of the ELC.”
What happens if you accidentally top off an ELC with a conventional coolant? “An ELC should tolerate a small amount of a conventional silicate coolant without any problems,” Granger says. “But, if you added any more than about 15 percent of the coolant capacity of your equipment, you should have it tested to verify carboxylate levels.”
Greg Northcutt is a freelance writer based in Port Orchard, Wash. He can be reached by e-mailing this publication at editor@onsiteinstaller.com.
