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[Big_Roger]

Hi,
I would just like to comment of one of the replies in this thread.

Th Vx red anti freeze is ethylene glycol based and definately not propylene glycol based so do not base any assumptions on the ratio / freezing tables in the link.

I understand the ideal mix for anti freeze is 30% to 50% which will cover just about all the conditions likely to be encountered in Europe.
A stronger mix does not improve anything, and is a waste of money.

In extreme conditions, ie Polar regions, engine coolant is based on glycerin or Poly Alkd Glycol oils, not stronger mixes of anti freeze.

The so called long life anti freeze, Vx red being one of them, are rated for about 5 years, this is nothing to do with their effectiveness as anti freeze, but for how long the anti corrosion inhibitors are effective for.

The "old" anti freeze used to be rated 2 years, but few drivers, or garages ever changed antifreeze, hence the problems of corrosion with oil coolers and the V 6 engines on susceptible cars such as the Omega.

Most of us are happy to change engine oil at regular intervals, just apply the same logic to the engine coolant and save yourselves a lot of uneccessary possible expense.

Roger.

[Abiton]

Yeah, apologies Bandit 127 (and other readers), I made a couple of unwarranted assumptions; sorry to have supplied potentially misleading info.  Thanks Big_Roger for the clarification on what's in the Vx coolant.  

 

[HerefordElite]

Water is nearly the most efficient heat carrying medium.  "Coolant" in the terms of antifreeze is added to counteract the side effects of water - i.e. supports corrosion (as is holds dissolved gasses far too easily), freezes at 0 degrees and boils at 100 degrees..

Add to much and the "coolant mix" can't actually transfer the heat away from the engine internals efficiently enough. Run a car on 100% antifreeze, and you actually stand a chance of it overheating....

...and freezing. The freezing point INCREASES as the mix gets greater amounts of anti freeze than 50%. The freezing point of 100% is -6 deg C, IIRC.

With respect, I'm not sure that you do remember correctly.  Have a look at the first table on this page: http://www.engineeringtoolbox.com/propylene-glycol-d_363.html

I imagine Vx coolant will be propylene glycol based these days.  The table only goes up to 60% concentration, but the trend is clear.

 

totaly agree 100% glycol would be perfect mix as regards feezing and boiling points but it comes down to specific heat capacity i.e. how much heat the medium can carry away where 100% water would be perfect (but your block would rust quickly and there would be reactions between disimilar metals).

so i guess somebody decided a 50/50 mix would be best??? not convinced though so gonna investigate more

(opens can of worms and stands back)
 

Sorry guys - this is the bit I didn't remember correctly. 100% glycol freezes about -12 deg. Not 6.

Have a look at what happens after 60%.

http://www.gi.alaska.edu/ScienceForum/ASF6/680.html

very well found Bandit guess that ideal mix is 60% glycol so suggested 50/50 mix allows for a bit of tolerance and gets best properties.

(Puts lid back on can of worms and logs off )