Why anti-freeze is an ‘all year round thing’.

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Anti-freeze does more than ‘what is says on the tin’. It’s an anti-corrosive too. Get it wrong and trouble is around the corner.

Traditional blue ethylene glycol is toxic but a highly effective antifreeze; it contains silicates as an inhibitor to help prevent corrosion in engines with mixed metals in their makeup. Bluecol and Blue Star are well known brand names, both are declared suitable for ‘classic cars’ on their company websites.

Propylene glycol is another well-known and less toxic antifreeze formula and usually contains silicates.

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, 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.

Another 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 is not recommended for use in historic vehicles. FBHVC is still researching this problem but its current advice 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

The above article is courtesy of Federation of British Historic Vehicle Clubs (FBHVC).

See Classic Chat, November 2016 for more information.

Paul Gough

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