"waterless" coolant

[djm16]

Since this bug-bear has cropped up again in a different thread, and one of our local club members is planning to put it in his P6 (against my advice), I thought I would list the very large number of cons.

Waterless coolant is simply 100% glycol (you could buy the same stuff - anti-freeze concentrate - over the counter at Halfords and not dilute it). It may contain ethylene glycol or propylene glycol or a mixture of both.

Only pro:
- it has a higher boiling point than water so will not tend to boil over when the engine overheats.
(it is doubtful whether this really is a pro, since the first warning most people get that their engine is overheating is first the smell of coolant boiling over, then the clouds of steam. In addition, the latent heat of vaporisation is significant and will continue to cool the block even when coolant levels are dangerously low)

Cons:
1) it carries less heat than water / glycol mixes
2) it is more viscous than water / glycol mixes so will circulate in the head and radiator more slowly
3) as it is more viscous, there will be a thicker un-stirred layer in contact with the block / head / radiator core so heat transfer is slower and needs a higher temperature gradient for the same heat transfer rate
4) the combination of 1-4 above guarantees that if your cooling system is only just coping (or less) with flat out driving, then you will have an overheating issue
5) pure glycol is flammable and has led to engine bay fires when it leaks

[enigmas]

Interesting! I didn't know that it was 'pure' glycol... and even if it wasn't, the product didn't make any sense to me as a coolant under any of the definitions for long life coolant.

I knew it's ability to transfer heat was poor and that its prime selling point, is that it's a 'good' product for engines (and cooling systems) that are stored for lengthy periods of time with little use...that's the advertising hype, not my view.

Interestingly, I stored my MG Magnette for 15 years (with an appropriate mix of glycol and water) without any deterioration to the cooling system. I wouldn't have started it more than 10 times during this period and for only 20 - 30 minutes on each occasion. The car still uses the same radiator.

[Warwick]

I really only know about the stuff from what I've read in other threads, so my comments are based on the impression I've formed - nothing more. It did seem to me that one of the main sales messages was that it contained no water, and as we all know, water is corrosive to the metals used in engines, therefore no water MUST be better. Since the addition of corrosion inhibitors to cooling system water overcomes this problem, then the main advantage of the waterless product is reduced maintenance. Add and forget. But there are other reasons to periodically drain the system, flush it, and replace the coolant. The only problem that I can see that it would absolutely prevent, is the corrosion that occurs between a rubber hose and the outer surface of the aluminium or cast iron spigot (thermostat housing, heater tap, head outlet/inlet, etc.) where there is a trapped film of static coolant. The corrosion inhibitor becomes depleted and surface corrosion occurs. But I suppose it does make sense if you are lucky enough to own a fleet of classic cars that are only driven occasionally. (I would really like to have that problem).

Personally I will stick with good old Castrol antifreeze. I have used it in every car I have ever owned, as well as numerous company cars, and never had a corrosion problem. My father used it before me. This was simply out of necessity. We were a skiing family and took the cars to the snowfields many times each year. (Yes it does snow down here. The snowfields in the Mt. Kosciuszko national park alone cover a greater area than the snowfields of Switzerland. What we lack is not area but altitude. And if you think Kosciuszko looks Polish, it's because it is.)
The only car I never used it in was my Citroen GS. No matter how carefully I poured it into the cooling system, it just ran out onto the garage floor. So I gave up.

I did learn something interesting from a fellow RCCA member a couple of days ago. Apparently ethylene glycol addition prevents cavitation; presumably by changing the surface tension of the water. This in turn prevents cavitation erosion of the water pump body and various points in the waterways in the head and block. He used to work for a major tractor manufacturer years ago and they discovered that farmers in the UK did not experience cavitation erosion in their tractor engines, whereas the prevalence in the same tractors in Australia was significant. Why? Because UK farmers used antifreeze, because they had to. Australian farmers usually didn't. So they studied the problem and discovered that it was the lack of glycol.

[enigmas]

Interesting Warwick. I'd also assume that Aussie farmers (being typical Aussies) would have used dam or bore water as a coolant in their tractors. There's no better coolant than water, but it does have specific issues when used without a combination of additives in iron and more specifically alloy engines. Adding glycol to water actually reduces the cooling ability of water. For the last 10 years I've been using 'Redline Water Wetter' either on its own with demineralised water in my Harley Davison Vrod (all alloy water cooled engine) or a combination of glycol and water wetter in my P5 Rover coupe. This car was also a daily driver until several years ago and manages very well in the temperature extremes of Australia's weather.

[djm16]

Enigmas makes a valid point that is alluded to in the P4 Drivers Manual. That there is a "Summer" coolant (water and corrosion inhibitor) and a "Winter" coolant (water and glycol and corrosion inhibitor).

Because we frequently get sub-zero temperatures in WA in winter and freuqently get +40 temperatures in summer, my coolant gets changed twice annually.