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Jun 12, 2023

Engine's coolant system needs seasonal maintenance

The antifreeze – or coolant – in the engine of your petrol-powered vehicle is

The antifreeze – or coolant – in the engine of your petrol-powered vehicle is somewhat like the air humans breathe. It's taken for granted until there isn't any, then bad things happen. Engines seize, humans wheeze.

Coolant is remarkable stuff that keeps vehicles moving in the dead of a Polar Express winter or the heat of Borrego Springs in late August. With proper seasonal maintenance, engine coolant – the combination of antifreeze and water – keeps the cooling system from corroding, boiling over and freezing. It's an interesting story of chemistry and automotive innovation, say the experts at AutoMD.com.

"If there's anything you should remember about coolant, it's this: don't trust the color," said Brian Hafer, V.P. of Marketing for AutoMD.com. "What started out as plain old neon green fluid for all cars, has evolved from that key identifier to today's bright variety of colors. It's like orange has become the new green – as well as blue, yellow and pink."

Today, all these colors help define the three basic types of corrosion-inhibitor packages, he said. And to help car owners understand the basics, the AutoMD team compiled the following guidelines and insights:

Coolant 101:

• Engine coolant is a mixture of antifreeze/coolant, de-ionized water, corrosion inhibitors, and dyes. A proper mixture is important because it prevents corrosion of the cooling system components, raises the boiling point and lowers the freezing point. That's how one fluid can protect in summer and winter.

• Most antifreeze/coolants contain ethylene glycol (EG) – a slightly sweet smelling chemical that is poisonous to animals and humans. Propylene glycol (PG), which is less hazardous, is also used. Both are still toxic when drained, and should be disposed of properly.

• EG and PG raise the boiling point of coolant, and lower the freezing point. The glycol fluid by itself doesn't, however, carry heat away effectively. That's what water is for, and why diluting antifreeze/coolant with water is so important. A 50/50 mixture is normally recommended and often sold premixed.

• The corrosion inhibitors in engine coolant will break down over time, which is why you should change it periodically. Follow the manufacturer's recommendations for the type of fluid used and the service interval.

3 basic coolant technologies:

• IAT: Inorganic Acid Technology is the traditional green stuff that is pretty much only used on older cars that predate the late 1990s. The lifespan of traditional coolant is about two years.

• OAT: Organic Acid Technology is used today because it offers silicate-free protection of all metals, and for a longer period of time: it's the long life (LLC) or extended life (ELC) coolant and has a service life of five years or 150,000 miles. Colors are mostly red and orange, but also green, pink and blue. (Silicates are corrosion inhibitors used in the traditional coolant, but if the coolant is not replaced at the recommended interval, silicates could cause deposit build-up inside the cooling system. OAT uses longer-lasting inhibitors – organic acids – to protect engine components.)

• HOAT: Hybrid Organic Acid Technology. This is also used today, and is usually orange or yellow. A mix of IAT and OAT, the orange cocktail – and only the orange – contains 10 percent recycled coolant.

About coolant colors

It's likely that manufacturers of coolant could have simply replaced green with green. But there's really no fun in that, said Hafer. "Some say General Motors started it with the neon yellow hues of Dex-Cool, and others point fingers at VW and Audi for bringing over the coolant that had been used for years in Europe."

Coolant FAQs

When should I check coolant levels? It's a good idea to inspect the coolant level at every oil change. Most new cars today operate with coolant good for 100,000 miles or more – but severe driving or other factors may change that. San Diego County is considered a severe climate for engine wear because of traffic congestion, summer heat and cold in the higher elevations. Best tip: the next time you open the hood, check the coolant level in the reservoir and give your radiator hoses a visual check and squeeze. Squeezing the radiator hose can help determine deteriorating rubber (cracking) or leaks.

Can I just add water to the radiator? ONLY in an emergency. Adding water to already-diluted coolant encourages rust and corrosion.

Do I have to mix antifreeze/coolant with water to a 50/50 mix? That's the ideal dilution for most climates. A 50/50 mixture represents a compromise between cooling efficiency and the ability to prevent the mix from freezing. Always follow the manufacturer's recommendation if you live in an area with extreme temperatures.

Can I just replace yellow coolant with yellow coolant? No. Check the vehicle owner's manual and be sure you use the recommended type of coolant.

Can I replace my vehicle's coolant? Yes, but follow common sense safety procedures, such as wearing safety glasses. Most importantly, keep a sharp look out for coolant spills. The fluid has a sweet sort of smell and taste to it, which may attract pets. Even a small amount of coolant ingested by the family dog or cat can have serious consequences.

Info: AutoMD.com is a free online automotive repair resource with how-to guides, troubleshooting, videos and more.

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