Dave Porter, long time Healey nut and general all round good guy, suggested that I take some time to enlighten readers as to the finer points of antifreeze which, like most things in our world, has become a much more complex subject that it was just a few years back. He pointed me to an article on the Master Technician site by Bob Freudenberger which surely emphasized that!!
In the old days, well since WWII, all we had was the old reliable “green stuff”. (Prestone used to dye theirs yellow-gold but it was the same stuff to all intents and purposes) “Green stuff” consists of about 95% ethylene glycol and the rest is corrosion and erosion inhibitors like silicate phosphate and tolytriazole, sodium benzoate which is an organic acid that is also added to Coke (the drinking kind), some dyes and 1 or 2% of water. This brew works very well although over time the corrosion inhibiting properties deteriorate over time. So you should do a flush and refill every 3 – 4 years.
Unfortunately many of today’s manufacturers and less than enthused about these concoctions and all manner of new and fancy antifreeze mixtures have appeared on the scene in the last few years.
These of course include GM’s DexCool which has gained something of a bad reputation and at last count there were at least 14 class action lawsuits filed in state and federal courts throughout the U.S. representing GM vehicle owners angered over their experience with this product.
Dexcool is based on OAT (Organic Acid Technology), and its additive package according to GM’s literature can keep corrosion away for up to 150,000miles. It seems that the big problem is that Dexcool doesn’t like air. Everything is hunky-dory just so long as the cooling system remains completely full of coolant but introduce some air and things go seriously pear shaped and the additives in these OAT type antifreezes produce a guckey goop which clogs coolant passages and generally creates havoc in the victim’s cooling system.
Additionally, one of DexCool’s ingredients is sodium 2-ethyl hexanoate which is a “plasticizer” . Plasticizers soften plastics which, as you can imagine, isn’t exactly ideal for use in engines which have water heated intake manifolds made from the plastics that these ingredients soften.
There are other OAT based antifreezes out there and these include Prestone’s new Extended-Life gold is and Wal-Mart’s Super Tech brand. I would suggest avoiding the use of these in any vehicle. However…I digress.
So what should one use for antifreeze in a Healey? The short answer is “The green stuff and not too much of it”.
Based upon the number of questions posted on the Healey newsgroup about overheating problems this does seem to be a major issue with Healeys. I distinctly remember participating in the rally during an event in Tahoe a few years back during which the last section was a long climb in the desert heat. The further we climbed up the slope the more the side of the road was littered with steaming Healeys. At one “Kodak Moment” vantage point it was difficult to find a place to pull off to take a photo!!
It has been my experience that if the cooling system of a Healey is in good condition overheating is not a problem and as many of us don’t drive our cars in the winter here is something to consider.
Water Ethylene Glycol 50/50 mix
Freezing Point 32F 8.6F -36F
Boiling Point 212F 387F 225F
Specific Heat 1.00 .57 .81
Thermal Conductivity .60 .25 .41
I’m no thermodynamics specialist but as I understand it the specific heat value is a reflection of the amount of heat a given weight of fluid (coolant) can transport. Now if the 50 / 50 water-antifreeze mixture in your cooling system can only carry 80% of the energy pure water can it seems obvious to me that I would want water and just water in my cooling system. Sure it may boil at a 13 degree lower temperature but if the system is working 20% better it probably won’t ever get that hot.
There is no question that if you live in a part of the world where the temperature drops significantly below freezing on occasion you need to have some type of anti freeze protection in your vehicle’s cooling system but this sure isn’t required in summer when overheating is the “issue of concern”.
One consideration of course is that pure water doesn’t provide much in the way of corrosion protection, but you can buy straight corrosion inhibitors to add to your coolant to solve that problem. One source is:Here and I’m sure there are plenty of others.
The reverse situation also applies. At the beginning of the cold weather here in the Great White North most auto repair shops get a number of customers coming in complaining that their heaters aren’t working. The most common diagnosis is that the heater core is plugged and the customer has to either put up with freezing feet for the duration of the winter or part out with a hefty wad of dough to have the core replaced. The fact is that in a fair percentage of cases the problem could be resolved by just checking and adjusting the percentage of antifreeze in the cooling system. We used to check the antifreeze concentration as part of a regular service and many was the time when we would discover that the cooling system had more than 70% antifreeze. Definitely a case of more is not necessarily better!!