Understanding Anti-freeze

Technology moves forward and new products are constantly being launched with claims to improved formulations and performance. As we found out with the bitterly cold weather in January 2010, antifreeze can hit the headlines, with some alarming stories reported which at first seem to be about the well-known tendency of antifreeze to find the tiniest hole and cause leakages – but in these cases it has led to catastrophic engine problems.

Traditional blue ethylene glycol is a toxic but highly effective antifreeze and contains silicates as an inhibitor to help prevent corrosion in an engine with mixed metals in its make-up. Bluecol and Blue Star are well known brand names and both of these are declared suitable for ‘classic cars’ on their company websites. Be aware that there are also low- or no-silicate ethylene glycol formulations (usually red) available which may not be suitable for all engines. Propylene glycol is another well-known and less toxic antifreeze formula and usually contains silicates but Comma, the main manufacturer, have now discontinued it in favour of an ethylene glycol product containing ‘bittering agents’ to make it less palatable and minimise the risk of accidental poisoning.

Both of the above products use inorganic additive technology (IAT). Recently problems have been reported concerning the use of antifreeze mixtures using organic acid technology (OAT). OAT was introduced in the mid-1990s and the products are biodegradable, recyclable and do not contain either silicates or phosphates and are designed to be longer lasting. However these products do seem to cause problems in older engines; over and above the ability of antifreeze to find the smallest crevice and leak, OAT antifreezes have been accused of destroying seals and gaskets and causing a great deal of damage in ‘old’ engines. For this reason the manufacturers do not recommend their use in historic vehicles. These products are usually coloured red, pink or orange.

The final category is HOAT. These products use hybrid organic acid technology in an ethylene glycol base with some silicates in the formulation alongside the organic corrosion inhibitors. The product is usually coloured green and are not recommended for use in historic vehicles.

The Federation are still researching this problem but our advice at the moment is:

  • only use blue coloured IAT antifreeze in historic vehicles;
  • only use OAT products (‘advanced’ or ‘long life’ antifreeze) if the vehicle used it when new and if specifically directed by the vehicle’s manufacturer;
  • never mix different types of antifreeze without thoroughly flushing out the system;
  • always replace the coolant within the time scale specified by the antifreeze manufacturer as the corrosion inhibitors break down over time.

Holden’s – 4Life Advanced Engine Coolant/Anti-Freeze is a proven advanced coolant for road & track. Uses latest additive technology to provide the highest levels of protection for classic & performance cars with normal pressurised cooling systems. 4Life’s Coolant/Anti-freeze has a boiling point of 180 degrees C at 15 p.s.i. for extra safety margin, has no coolant loss though evaporation and has an anti-foam agent that prevents engine hot-spots. 4Life’s Coolant/Anti-freeze additive gives you 10 years of protection to -42 degrees C (which removes the need for bi-annual coolant change), preserves rubber hoses, gives protection from frost expansion damage, and is PH balanced with no acidic impurities or lime scale. For more information and to purchase, click here.

Bluecol – Bluecol 2 Year Antifreeze & Summer Coolant is a methanol-free, ethylene glycol based antifreeze and engine coolant. Keep Bluecol in your radiator system throughout the year to maintain maximum protection against winter freezing to -36°C and summer overheating, whilst at the same time protecting the materials in the cooling system against rust and corrosion. Bluecol 2 Year is suitable for all engine types, including aluminium. It does not evaporate in use and is not flammable. * Does not incorporate Organic Acid Technology (OAT). Suitable for classic cars. For more information and to purchase, click here.

Carplan Blue Star – they state on their website that “Blue Star Anti Freeze and coolant has a powerful formula with 2 years protection for all seasons. Using IAT technology it is suitable for all vehicles including Classic Cars.” For more information and to purchase, click here.

It would appear that Blucol and Carplan Bluestar are made by the same people but that does not mean it is the same product.

There may of course be others and one recommendation is for BMW Blue anti freeze or coolant as it may be referred to. Nothing is known apart from “BMW Anti-Freeze/Coolant contains no Nitrates or Phosphates and has been formulated to prevent excessive silicate dropout”.

“I have just returned from chatting with the foreman of my local Jaguar workshop in Western Australia. The shop uses and recommends Castrol “Radi-Cool” for all their Jags. The following technical data on the side of the container reads as follows:-
The “Radi-Cool” comes in either concentrated or premixed form. The pre mixed coolant contains 33% ethylene glycol and 10mg/kg of denatonum benzoate – max bp elevation 109 degrees C (no mention of corresponding pressure). Further, the coolant exceeds the Aust. Corrosion Studies Standard (AS 2108.1) and has a 3yr /60 000km service life – approx $22/5L in Aust.

I note that Castrol also produces an inhibitor called “Radi-Cool” as well. The Radi-Cool inhibitor comes in 200mL containers, 45% of which (not sure if it is by vol or mass) is glycol and contains benzoate as well. One can or approx $5 Aust. worth will treat a small cooling system. I suspect that the inhibitor composition is very similar if not the same as the coolant except for the glycol percentage. The note on the side of the inhibitor container states that the inhibitor can be mixed with the Castrol Radi-Cool coolant.

In summary, I feel that the best prescription for my cooling system is either the Castrol inhibitor+ distilled water or 33% premixed Castrol coolant if I want a degree (excuse the pun) of bp elevation. It’s nice to know that I can mix either freely if I change my mind and require a higher bp afforded by the 33% glycol mixture.

I need to build a new radiator, so I will include the necessary fittings to feed a semi sealed fluid recovery tank. I will take the jag shop foreman’s advice and change the coolant at least every two years. Irrespective of the brand of coolant/inhibitor, I believe that this last point is probably the most important.”

A suggestion extracted from a Forum
What about Evans NPG coolant? Their website, http://evanscooling.com/main22.htm claims it as a cure-all for all ills including overheating since it boils at 190°C. It is a non-aqueous propylene glycol coolant, apparently non-corrosive and non-toxic. I think it is available in the UK, try EBay. Anyone used it or have experience with it?

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