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It*s Time To Check And Change Engine Coolants

Cold weather is approaching. If you own water-cooled equipment such as cars, pickups, trucks, tractors and combines, it*s time to check the freeze level of the coolant in the radiator and cooling system or replace with new coolant mixture if the mixture has not been changed according to your maintenance schedule.

Most of the antifreeze products on the market currently are ethylene glycol base material with additives to prevent corrosion, lubricate seals and water pumps and aid in heat transfer to the coolant from the metal of the engine. Antifreeze should be mixed with distilled water (tap water contains high amounts of minerals such as calcium and iron that can precipitate and coat internal parts) at the ratio of one part antifreeze to one part water. This gives freeze protection down to minus 34 degrees and boil-over protection up to +265 degrees. Never use pure antifreeze in a cooling system without using at least 30 percent water in the mixture. Most antifreeze products sold for the past several years have been the traditional "green" coolant. This type is good for two to three years and up to 30,000 miles. The green antifreeze contains silicates, phosphates and / or borates as corrosion inhibitors to keep the solution alkaline. As long as the solution remains alkaline, corrosion is controlled and the system is protected. Over time, the corrosion inhibitors will be depleted and the corrosion protection is lost. It is for this reason that green antifreeze should be changed every two years or so. Aluminum is especially vulnerable to corrosion and many vehicles have heads, radiators and other aluminum components in the cooling system. If the coolant in an engine cooling system is changed before corrosion inhibitors reach dangerously low levels, corrosion damage is prevented.

An alternative to tradition green antifreeze is a product currently used by many engine manufacturers. "Orange" antifreeze is a long life or extended life type of antifreeze used to increase the useful life of engine coolant. It is ethylene glycol base as is the green antifreeze. The difference between the two colors is that orange antifreeze contains a different type of corrosion inhibitor that has a much longer service life than silicates, phosphates and borates. Orange antifreeze contains organic acids that protect engine parts from corrosion. Silicate (green) type antifreeze does not mix with orange type antifreeze. Never mix the two colors in a cooling system. The organic acids in orange types will cause precipitation of silicates in the green type and corrosion protection is greatly reduced. Orange type antifreezes are good for five years or 100,000/150,000 miles in newer vehicles (1996 and later). They can be used in many older vehicles (ask your vehicle dealer if it is safe to use orange antifreeze) if all of the green mixture is flushed from the system and is replaced with the orange mixture. Useful life is about four years or 60,000 miles in older cars.

Toyota uses a red antifreeze in many of its products and should not be confused with the orange type long life antifreezes. It is essentially the green type of antifreeze that contains red dye to give it the red color.

If you have doubts about switching from the red or green type of antifreeze to the new orange extended life antifreezes, contain your equipment manufacturer or dealer and ask about compatibility with your engine parts and cooling system.

Cummings diesel engines have silicone seals in the engine and do not recommend use of orange antifreeze because the organic acids will cause degradation of the seals after 80,000 to 100,000 miles of use. Coolant can leak past damaged seals into the engine lubrication oil system and plug oil filters with resulting damage to the engine.

The freeze protection level of a coolant mix has little relevance to the corrosion protection afforded by the coolant mix. The freeze level of the mixture may test to a satisfactory protection

level, but corrosion protection may be depleted from time of use. Change your coolant mix on a schedule based on the color of the antifreeze you are using. Severe corrosion to engine and cooling system components can occur with resulting expensive repairs.

James B. Wills, Jr.

Agricultural and Biosystems Engineering


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