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Granddad was right. A vehicle's antifreeze needs to be regularly drained and replaced with a mixture of half antifreeze and half distilled water (although pre-diluted formulas are available). If you or Grandpa forgot the "distilled water" part, it's time to replace your antifreeze, even if it was changed yesterday. While Gramps was right if he advocated biannual or even yearly changes, new-fangled, longer-lasting antifreeze can increase the interval to five years. (If the old man was a hippie and drove an air-cooled Volkswagen Microbus, ignore him.)
Antifreeze, which is also called coolant, serves two major purposes. First, it prevents ice from forming inside a non-running engine: If the coolant inside the engine freezes, it expands with a force that can crack even an iron engine block. Second, but just as important, antifreeze raises the boiling point of water and helps the radiator to efficiently transfer engine heat to the air.
It's All Glycol To Me
There are two types of antifreeze, the traditional ethylene glycol and the relatively new propylene glycol. Performance will be indistinguishable to almost all motorists. The big difference is propylene glycol is far less toxic to animals than ethylene glycol. A few licks from a spilled puddle of the sweet-smelling ethylene glycol can kill a dog, cat or child. While propylene glycol is far less toxic, an old dog or cat with kidney problems may not survive drinking a half-cup or so.
Antifreeze and the Environment
While both forms of antifreeze biodegrade quickly into nontoxic components, it's not okay to dump used coolant in the gutter or landfill. Used antifreeze is classified as a hazardous waste and must be deposed of at an approved collection point. (Check your county government's website for locations.) The reason: Coolant picks up dangerous heavy metals, such as lead, cadmium and chromium, from inside the radiator and engine. Also, antifreeze will kill fish and other wildlife while it's biodegrading.
Similar to motor oil, ethylene glycol and propylene glycol don't wear out and can be recycled. The main reason to change antifreeze is to renew anti-corrosion additives and remove contaminants. A recycling company can remove impurities, add new corrosion inhibitors and the antifreeze is ready to go another two years.
Led by Distilled Waters
The reason only distilled water should be mixed with antifreeze is that the water from your hose contains chlorine and other minerals. These make the water safe and even tasty for humans to drink but contribute to the formation of deposits inside the engine water passages and the radiator. These deposits insulate the engine's heat from the coolant and can block radiator passages. Additives in the antifreeze are designed to prevent deposits from forming, but using tap water makes them less effective and wears them out sooner. It's important to avoid handicapping the cooling system because carmakers now employ high combustion-chamber temperatures to lower emissions and increase fuel mileage.
Mixology
For almost all of the U.S., the proper mixture is half antifreeze and half distilled water. With a radiator cap that keeps pressure inside the cooling system at 15 pounds per square inch, a 50/50 mixture won't freeze until around minus 30 degrees F. Alaskans can run two-thirds antifreeze and one-third distilled water to drop the freezing point to about minus 60. If it gets colder than that leave the engine running.
Just as important, a 50/50 antifreeze/water blend raises the boiling point to more than 50 degrees above that of water. If the coolant mixture boils, the water pump will move less coolant because of the bubbles caused by boiling. In addition, older hoses may burst from pressure spikes. With an "all-aluminum-alloy" engine, calamity strikes well before the boiling point of a 50/50 mixture.
For about $10, an "antifreeze hydrometer" will tell the obsessive exactly the mixture of antifreeze and water in their system.
Never use run straight antifreeze. Some additives need water to work. Also, not only will straight antifreeze put an extra load on the water pump, it has a warmer freezing point than antifreeze mixed with water.
While there's nothing in their chemistry that says ethylene glycol and propylene glycol can't be mixed, check your vehicle owner's manual and the labeling of the products before doing so.
Live Long and Prosper
Long-life antifreeze is made possible by employing a different type of additive-organic acids-to prevent corrosion and deposits. Many extended-life antifreeze brands use both this and traditional inorganic acids. Before mixing long-life and traditional antifreeze, make certain both your vehicle manufacturer and the antifreeze producers say it's okay.
Don't Flush
Gramps was wrong about one thing: Flushing your radiator won't help and may hurt. If your antifreeze hasn't been replaced since George W. Bush's first term, there's nothing you can do to usefully remove the deposits that have built up on the inside of your engine and radiator. And running water backwards through the engine might cause debris laying in the bottom of the radiator to lodge in its passages. If your car is overheating, it's likely the radiator may require professional attention and, possibly, replacement. There are a number of other potential causes, including a stuck thermostat, a slipping engine cooling fan, a failing water pump, a bad radiator cap or air trapped in the cooling system. If your car wasn't overheating before you replaced the antifreeze, most likely there's air in the system.
Easy Does It
It's easy to change your coolant. The biggest problem will be finding a container that will hold four or five gallons (check your owner's manual). With the engine cool, open the petcock (it looks like a "T") on the bottom of the radiator. If your radiator isn't so equipped, remove the lower radiator hose from the radiator. Close the petcock or reattach the hose. Fill the system with half antifreeze and half distilled water. Finally, bleed the air from the system, using directions in the owner's or repair manual.
Regularly replace your antifreeze, mix it 50/50 with distilled water, take the old antifreeze to a recycling center and both you and your car will enjoy happiness-at least to some degree.
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