<< Time doesn't degrade anything. Glycol needs oxygen to degrade >>

I don't think you should get away with repeating this rather simplistic suggestion. As you imply, chemical reaction is necessary, which by definition takes time, the rate depending on concentrations and temperature. I doubt that many 'closed' systems (which you imply) are truly hermetically sealed. Hence the much-discussed advice to change fluids after [a] mileage covered and/or [b] time elapsed.

John, I don't think your TR7 will have done anything like 250k miles, ......

True, currently just over 73k

Your suggestion, if universally valid, should apply to any vehicle of 1980 vintage, but I have seen an early Clio with what looked like Windsor soup in the coolant reservoir - partly because the car's maintenance manual made no suggestion that coolant needed changing, which it clearly did. Or at least examining to check ?

I doubt if not changing it caused the W soup. Far more likely would be the mixing of oil and coolant caused by CHG failure. Indeed, one could argue that frequent changes introduced regular supplies of corrosive oxygen thus causing CHG failure.....

Most 20th-century cars recommended coolant changes (perhaps more often than really necessary) for a good reason - that it degraded with time.

Time doesn't degrade anything. Glycol needs oxygen to degrade - see argument above.

The reservoir was also semi-transparent to make that more obvious.

You could see the reassuring pink of the never changed coolant in the semi-transparent reservoir of our 21yr old 160+k mile Focus as it trundled off tothe scr@pyard, thanks to the action of corrosive oxygen on its nether regions.

I had that Windsor Soup stuff in my Skywing in Taiwan.

I suspect this was due to me using a local brand of antifreeze. Things seemed to improve when I got some Shell stuff.

If the simple exclusion of oxygen from my nominally sealed system were sufficient, I should have been finer than thou, since, unlike thou (I assume) it was my routine to bring the coolant to the boil before sealing (which should have driven off dissolved oxygen) since otherwise I got air pockets which took a long time to clear.

Not definitive, though, since I suppose its possible that I would have been OK with boiled tap water, and it was the breakdown of the c***py coolant that caused the problem

When I was choosing an antifreeze primarily as a rot-treatment, but also to flush my seawater cooling system for storage, I came across this

www.ryeoil.co.uk/shop/classic-antifreeze/

Inorganic acid technology (IAT) antifreeze, also known as fully formulated coolant, is a traditional type of coolant that contains ethylene glycol, phosphates, and silicates. It’s usually green or blue in colour and is often used in older vehicles, particularly those manufactured before the late 1990s. This antifreeze is designed to protect cast iron, brass, copper, and aluminium parts in older vehicles, and it also contains supplemental coolant additives (SCA) to prevent engine lining corrosion. The Classic antifreeze employs established inhibitor technology and is nitrite, amine and phosphate (NAP) free and includes borate and silicate.

This seems to imply that "traditional" IAT stuff, often described (by Halfords, for example) as "Silicate", would be recommended for the OP's use, and I'd guess that's probably what he's using, but apparently it isn't very good.

Thats what I used too,(as concentrate) though for a different couple of applications.

Most block castings seem to have "unused" cooling passage ports which are blocked off by the head gasket and may be for the removal of casting sand in production.

If I was going to position protective anodes (perhaps magnesium) in the head (perhaps sections cut from one of the "pencil" type) and couldnt find anywhere to bolt them, I might put them in there.

www.anodeoutlet.co.uk/00713mg-volvo-penta-magnesiu.../

Edited by edlithgow on 28/11/2024 at 12:39

In that application, magnesium might be more effective.

https://www.anodeoutlet.co.uk/01303-zinc-anode-for-1gm-6ly3-yanmar-engines-27210.html

Particularly so as the (not very) TDS for the Comma Super Coldmaster stuff the OP is apparently using (The SDS, often more, though of course still not very, informative, doesn't seem to be there) notes:-

"Avoid galvanised containers for storage or dispensing as they will corrode and contaminate the product."

Oo-er.

That Comma stuff is probably very similar to the Halfords Silicate stuff I used, and I dont have the option of avoiding zinc, since a zinc anode provides essential protection to the engine.

I feel an alarmist post to some boating forums coming on.

Panic among the pirates.

<< 50/50 antifreeze / deionised water is the optimal mix you should be using.. Less than 50/50 concentration will result in long term dissimilar metals corrosion problems. >>

I suspect diluting concentrate with deionised water may be more important than you think, especially if the alternative is hard tap water. I'm not convinced that 50/50 strength is needed to prevent corrosion, and it certainly isn't to prevent freezing unless your car experiences arctic conditions.

You can think and do whatever you like, but I am telling you the standard engine industry dilution of antifreeze/water is 50/50 or sometimes expressed as 1:1.

It was that standard when I worked for an engine manufacturer, and afterwards when I was in business in the same industry. - a total of 25 years.