In my college physics class last week, we were talking about antifreeze, different mixtures, and freezing and boiling tempertures. Most people do a 50/50 mixture of antifreeze and water. With this mixture, it will freeze at -34*F, and boil at 227*F. If you pressurize it, the boiling temp increases. I believe on our cars, the mixture is under about 15 or 16 pounds of pressure. This raises the boiling temp to 262 to 264*F. That's overheated for our cars. If you do a 68% antifreeze, 32% water mixture, the freezing temp is lowered to -90*F, and boiling temp is almost 300*F when pressurized to 15lbs. 241*F not pressurized. However, antifreeze all by itself with no water added will boil at 320*F, but will freeze at only -8*F. So, never pour straight antifreeze in your car, especially if you live way up north where it gets that cold in the winter. Still, the best antifreeze mixture for most areas of the planet is 50/50. Water does cool better than straight antifreeze. So, to cool your engine off faster, you need more water. I'm pretty sure, that straight antifreeze doesn't expand like water, but I'm not totally sure. Water is one of only a few substances known to man that expands when it freezes. Anyways, I don't know if anybody cares. I just thought that this stuff was kind of interesting. If anybody is interested, I can scan my chart that shows the freezing and boiling tempratures for different mixtures and pressures. Matt

 

cool good info!

 

Interesting, evidently there is a synergistic action going on. Chemistry was never my strong point. By diluting ethelyne glycol by 50% one lowers it's freeze point. I'll have to ponder this. More info on the chemistry taking place would be helpful. Taking manufacturers info into play it does not look like coolant does much at the high end. Since for every pound of pressure you raise the boiling point of straight water 3 degrees, at 16 lbs you raise the water to 260 degrees before it boils. With a 50/50 mix the manufacturers state a 265 degree boilover temp. 70/30 mix they state 275 degrees. I am using inspection data from Texaco regarding Dexcool, perhaps since it is OAT based it may vary somewhat from conventional EG. my understanding was that it had the very same boil/freeze points. You got me thinking.