| 50/50 mix of distilled water and antifreeze will give a protection down to - 30 or 40c. Do not go more than 50 / 50 as this actaully has an adverse effect on the cooling properties.
Another way to go would be to use Texaco Havoline Extended Life Coolant. This is mixed with distilled water as per standard antifreeze, however, it has much better corrosion prevention properties, works well will ally engine parts and gives a 5 year life as compared to 2 years max with normal antifreeze. | 
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