Hi Andrew, I run all year round with a 50:50 mix of tap water (rain water is probably better) and a Mono Ethylene Glycol (Blue) antifreeze which I change every 2 years. I use "Morris's MEG based Antifreeze" as they are a local company whose products I trust but, many other manufacturers products are equally suitable. The critical thing is the Mono Ethylene Glycol bit.
Also, the changing every 2 years isn't because it has stopped working as an antifreeze, rather because the corrosion inhibiter contained within becomes ineffective after 2 years service.

Incidentally, " the 'green stuff' to be mixed with rainwater" sounds like instructions for imbibing Absinthe! LOL

Ian Mc.

Location: Shropshire

If you need anti freeze then a glycol mix, however if you want a coolant then water will conduct heat away better and if mixed with a "Water Wetter" that lowers the surface tension if will work better again. I use Redline Water Wetter in my Lambda mainly for the better cooling and very good corrosion protection.

But I'm in Australia where freezing is not an issue but overheating is.

Location: Rokeby, Victoria, Australia

You can buy ready to use coolant from a supermarket. It's green and usually goes by the name of all seasons. No need to use anything expensive. Beware though that ethylene glycol is thinner than water and will find leaks that you never thought you had...

Location: Gard, France 30960. Used to be Languedoc-Roussillon but now it's Occitanie

I use water from the dehumidifier and Fernox F1 central heating corrosion protector. Keeps everything very rust free

It would seem advisable to use de-ionised water if you ever want to remove the head studs, as this seems to inhibit galvanic corrosion (see induction heater thread).
I suspect any modern anti-freeze/corrosion inhibitor will suffice. An old trick I picked up was to syphon a little coolant into a container (yoghurt pot) and pop it in the freezer overnight. That's -20C or thereabouts and if it's still liquid when it comes out, then that's good enough for me.

Anyone who has compared the innards of a typical Seven block and head with anything made in the last 50 years when additives were more or less normal will appreciate that additives very beneficial. I have several 50 year old cyl heads from iron block cars and like new inside. Heavily rusted old Seven heads continue to absorb moisture and corrode lying about whereas the additive treated heads do not.
In Australasia categorised as Type A and B, the former anti freeze and considerably more expensive Type B which is just an inhibitor. Lots on Internet. The specific heat of antifreeze is apparently low and the cooling inferior. I gather Type B is used in competition engines. I have used it in my 1960s car for decades.
A problem with Sevens is tend to eject a lot of water under braking etc so a catch container reduces waste. No gharish plastic ones please.

It is somewhat irksome that on a low mileage vehicle coolant costs rival the oil!

Location: Auckland, NZ

An interesting point about NZ sevens is the level of corrosion inside blocks and heads when compared to UK cars. In my experience NZ cars ( certainly upper north island ones ) are in a significantly worse state than their UK counterparts, my theory is that due to warmer temperatures here few owner's ever have, or do use anti freeze. So much so that many otherwise good blocks when bored to just .040" break through into the water jacket.

Location: NZ

I'd definitely agree with the Fernox additive. It is designed to prevent galvanic action in central heating systems where there is the combination of cast iron,stainless and mild steel,copper, brass and lead/tin solder. It seems to remain effective even when much diluted.

Hi Ian

I suppose anti freeze was used in vulnerable inland areas but not commonly elsewhere prior to 60s. I worked in Christchurch and Dunedin at the time and never heard it mentioned by workmates. although it was added to employers Landrovers after frozen radiators descending tracks in low ratio from inland radio huts at 5000ft. The Seven survived 13 deg C frosts outside with just an old coat over the bonnet, the method used by many.
My guess is the semi tropical humid Auckland atmosphere is the problem. Most old blocks have lain about for decades. Can hammer old heads and rust flakes fall out and repeat 5 years later. If not saturated in clean engine oil old parts should have holes blocked off to stop air flow.
Over the decades my father and self have had tools and items stored in (windy and dry) Wellington, Levin and Auckland. Latter by far the worst; painted tin plate items like old style biscuit tins rapidly rust in Auckland.

Location: Auckland, NZ

So do they here in Brittany Bob, especially so when your workshop is 100 meters from the sea!
Renaud

Location: Unsunny Brittany

Excuse me for hijacking this thread. Would like to contact Duncan Grimmond about the construction of Benjaustin, as shown on the l'Amicale Tricyclecariste de France website. Thanks

Location: Hastings-next-to-France

Evans waterless coolant. No water = no corrosion. Used by many especially among classic car owners who have previously had to replace blocked/corroded radiators, heater radiators, engine blocks clogging up and overheating in local hotspots, corroded studs/bolts where they penetrate water jacket etc. Snag is preparation for use and initial cost, though long term savings likely.

Fernox good as previously mentioned.

Colour of any antifreeze now no longer a valid recognition due to various manufacturers of differing chemical contents mixing up colouring.

Believe the one to avoid is anything containing OAT (organic acid technology).......look it up to see why.

Dennis

Location: N W Devon

I had looked at using this is another car, what put me off was that you cannot mix it with water, so if you need to top up etc you can only use Evans Waterless Coolant,

Location: Fife

As Evans will not conduct the heat as well as water your car will run hotter but it will not boil, so in summer you will get hotter feet.

Location: Rokeby, Victoria, Australia

I looked at a similar product here a few years back, it significantly raised the operating temperature of the engine due to the poor thermal conductivity. Aside from that in an open cooling system we probably have a responsibility to other road users and should not to use it, it is extremely slippery on a wet road, extremely!

Location: NZ

And, perhaps, more fuel vaporisation!

Yesterday I changed the coolant on my Ulster in preparation for the coming hill climb and sprint season. 1.2 litres of traditional Ethylene Glycol based anti-freeze (£13 for 5 litres from Euro Car Parts) topped up with tap water. Always worked in the past and don't see why it shouldn't continue to do so. Draining off the old coolant that's been in there for 12 months, it came out totally clear with a slight blue tint. No sediment or rust coloured water whatsoever.

Steve

Location: North Yorkshire