ELC or XLC: What Type of Coolant is Right for Your Application? - Engine Builder Magazine

ELC or XLC: What Type of Coolant is Right for Your Application?

Which antifreeze should you use in your diesel engine? It seems just when you think that things are starting to settle down, something else changes.

Which antifreeze should you use in your diesel engine? It seems just when you think that things are starting to settle down, something else changes. Engine oil has been a hot topic over the past several months and has seen many changes over the past 10 years. Antifreeze has also undergone changes and seems to be a hot topic. The frightening fact is that many diesel engine owners are unaware of these changes, which could result in a major catastrophe down the road. 

Hopefully, this information will benefit you and your diesel engine customers.

For years we used the typical, green antifreeze formulation. Conventional heavy-duty antifreeze coolants used inhibitors known as SCAs (Supplemental Coolant Additives) that were composed of IAT (Inorganic Acid Technology), which are inorganic compounds such as silicates and phosphates. SCAs were very important in maintaining proper health for a diesel engine because they help prevent small air bubbles from forming around the cylinder liners, which could chip away at the liner. The chipping effect would eventually eat through the liner into the cylinder wall. When this happens coolant gets into the engine oil and combustion chamber and can eventually destroy the engine.

Heavy-duty, green antifreeze often needs a check on the SCA levels during maintenance intervals. If the SCAs are becoming depleted then a supplemental SCA known as coolant conditioner can be added to help boost levels of SCA back where they need to be. Conventional coolant does not have a very long life and should be changed roughly every two years.

Conventional Coolants

• Silicates for aluminum protection

• Nitrites for liner cavitation protection

• Other inhibitors for copper and iron protection

Toward the late 1990s, ELC (Extended Life Coolant) was introduced, which allowed for much longer intervals before the inhibitors needed to be replaced. ELC contained inhibitors known as OAT (Organic Acid Technology) or Nitrited Organic Acid Technology (NOAT), which deplete slower than traditional inorganic silicate and phosphate compounds. This type of coolant can be used for up to 300,000 miles or 6,000 hours of engine operation. Even at this mileage the coolant can be charged with an extender additive and continue for another 300,000 miles or 6,000 hours of engine operation. ELC requires little or no maintenance. It just needs to be checked every oil change for dilution, clarity, freeze point, and color. The color of ELC is usually bright red or pink. Typical ELC can go for up to a five year interval before changing is recommended.

ELCs (Nitrited Extended Life Coolant)

• Organic Acid technology for aluminum and iron protection

• Nitrites for liner cavitation protection

• Other inhibitors for copper protection

In order to save weight and add fuel economy some manufacturers opted to use aluminum radiators and other aluminum components for the cooling system. This was a great idea until it beame evident that aluminum components in the cooling system were becoming corroded and causing nitrite depletion in the nitrited coolant. The ELC coolant didn’t last as long and caused corrosion, leading to overheating and cooling system problems. The OEMs realized that unless the aluminum components were coated with a non-corrosive film such as metal oxide, the corrosion problem would exist.

With aluminum components in the cooling system there are two solutions to the corrosion problem. One is to have all of the aluminum components coated to combat the corrosion problem. However, this isn’t cost effective. The second solution is to formulate a coolant that can work in this cooling system environment and not have nitrite depletion.

This led to manufacturers incorporating the use of XLC (Xtended Life Coolant). This antifreeze uses what is known as an Aliphatic Carboxylate inhibitor, which is nitrite free and made with other somewhat proprietary ingredients. So far it works well as an extended life coolant with a longer drain interval than the ELC. The color of XLC has been typically known as orange in the heavy-duty market but may be offered in other colors.

XLCs (Nitrite Free Extended Life Coolant)

• Organic Acid Technology for aluminum and iron protection along with liner cavitation

• Other inhibitors for copper protection

Beware of how coolant has changed over the past 10 years. Remember, antifreeze when manufactured is a clear liquid. Different dyes are added to the antifreeze to indicate what type of coolant it represents. Water is the best collector of heat but the main purpose of antifreeze is not only to cool but to raise the boiling point and to offer freeze protection, which pure water cannot do.

Pay close attention to your antifreeze choices for automobile and heavy-duty use. Most antifreeze coolants will not mix, and if improperly mixed may cause major damage. Customers are learning that for modern day engines, going to the part store for simple things such as motor oil or antifreeze isn’t quite so simple. Help them choose the specific fluids that must go into their engine.

You May Also Like

Shop Solutions January 2023

Next time you have set of large journal small block Chevy connecting rods to resize, consider honing the big ends of them for a +.002” outside diameter bearing that the LS engines with fracture cap rods use.

Engine and Machine Shop Tips and Tricks


For proper block cleaning, the oil bypass valves in Gen 5 and 6 big block Chevys need to be removed. We made a couple different sized “hook” tools for a slide hammer. This tool will easily pull the valves out of the block and sometimes without damaging them.

Shop Solutions December 2022

Everyone misses occasionally, and this helps avoid dents and damage.

Jesel Certified Performance Rebuilds

Engine components are serious investments for any racer and maintaining that investment could be the difference between winning a championship and losing it.

Going the Extra Mile with Cylinder Head Porting

It’s not just the port work alone that creates spectacular cylinder head performance. The most critical areas of a cylinder head are those which pass the most air at the highest speed and for the longest duration. Your bowl area, the valve job, the throat diameter, and combustion chamber are all crucial parts. 

Tight Tolerances and Building Power

As you ascend Mt. Everest, you reach an area called the death zone. Once you climb high enough, the margin of error becomes perilously thin. That death zone also applies to engines. As the horsepower per cubic inch and rpm increase, the margin of error decreases. 

Other Posts

Engine Ice’s Ice Water Racing Coolant

It protects all engine parts, including cast iron, brass, steel, and rubber.

CNC Update: Features and Automation

Precision is key when it comes to automotive parts; the complex designs of connecting rods, pistons and rings, blocks, cylinder heads, and other parts require super tight tolerances that are getting more and more difficult to be met by hand or with other machining processes outside of CNC.

All Things Media Blasting

Engine building is a segment of the automotive industry that has always been ahead of the curve in media blasting, and no matter the engine shop, cleaning equipment is a common bond.

Engine & Hub Dynos: Necessary Tools and Additional Revenue

Being able to see the horsepower and the direct correlation to what is lost in the driveline is invaluable – dynos offer a myriad of benefits for the modern engine shop.