Interesting Facts

Ethylene glycol was first prepared in 1859 by Charles Adolphe Wurtz, a French chemist. It was looked at as an additive to nitroglycerin explosives to prevent freezing.
See History of Antifreeze

If you add ethylene glycol after getting to 68% mix its freeze protection falls, and at 100% it only protects to -20C. Propylene glycol coninues to protect all through the mix cycle and at 100% protects to -60C.  See Freeze Protection Comparison

Water is the most efficent heat-transfer fluid known. If it did not freeze when cold,  and boil when hot at too low a temperature, water would be the ideal heat-transfer fluid for automotive cooling applications. Adding either ethylene glycol or propylene glycol overcomes these water problems. Which is the better glycol? No surprise, it is Propylene glycol. Why?
    Non hazardous - lower toxicity - safer for animals, marine life, and humans
Will not damage paint
    Better heat transfer characteristics at engine operating temperatures
    Lower flow increase to achieve the heat transfer of water. See
   
What the AA states:

"For most people a car is a significant investment, in comparison the price of even the most expensive antifreeze/coolant is relatively minor. Purchasing a good quality antifreeze/coolant will help to protect that investment. Using a cheaper, inferior product could result in expensive damage to the cooling system or the engine and prove to be a false economy in the long run."

"Propylene glycol (PG) based antifreeze/coolant is offered as a less toxic alternative to ethylene glycol based products. They are used by people who are worried about the toxicity of ethylene glycol based products. No major vehicle manufacturers currently use PG based products for original fill, but PG based products are more widely used in Austria and Switzerland where there is legislation that restricts retail sales of hazardous products."

"As a rule of thumb, only about 28% of the thermal energy released by burning fuel in the engine is available for driving the car.
    * About 7% is used to overcome friction in the engine, drive train, tyres etc.
    * Another 35% disappears out of the exhaust, and
    * The remaining 30% has to be removed by the coolant or the engine block would go into melt down."

"Engines are constructed from several different metals and it's important to prevent corrosion and scale build up in the cooling system at normal operating temperatures. Around 60% of engine failures can be attributed to cooling system problems."
 
Wind Chill Factor

The rate of heat loss by a surface depends on the wind speed above that surface: the faster the wind speed, the more readily the surface cools. For inanimate objects, the effect of wind chill is to reduce any warmer objects to the ambient temperature more quickly. It cannot, however, reduce the temperature of these objects below the ambient temperature, no matter how great the wind velocity.


Saturday 4 December 2010
Overnight, temperatures fell as low as -20C in Braemar
-10C at Manchester airport and -10 in Yeovil.
The thermometer at RAF Leeming in North Yorkshire was showing -17.9C on Friday morning, making it the coldest night recorded at the station since records began in 1945. The daytime temperature at Leeming was -8C.
The Met Office has been keeping records of the UK weather since it formed under Captain Robert FitzRoy in 1854.
Lowest Temperature recorded in United Kingdom
-27.2°C Braemar, Grampian 10 January 1982 / 11 February 1895  
-27.2°C Altnaharra, Highland 30 December 1995

Classic Coolant 50/50 Pre-mix has freeze protection to -34°C