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MG TD TF 1500 - Antifreeze Colour

I am certain this topic will be in the archives but they are now so comprehensive that if used prior to every posting we run the risk of an empty bulletin board. Avid readers will know my cylinder head is off the engine. When the car was rebuilt a couple of years ago a new radiator, pump and hoses were fitted and the system filled with red antifreeze. The inside of the hoses and the thermostat are covered in rust coloured slime, as if I had simply used neat water. Does red antifreeze have corrosion inhibitors or perhaps the stuff I used was poor quality. I think after a good flush I will use the green stuff next time. Any advice?

Jan T
J Targosz

In the UK it is orange and green, the orange has the more robust set of additives, so should last longer. I am not therefore sure that you will find the green a better antifreeze.
Ian Bowers

Only thing I can ad is, never mix the two. Dexcool can turn slightly acidic if air is trapped in the system. Basically there is no reason to use anything other than Green in our old systems, but, there are some reds with the same formula as the green and all are ethanol glycole base. It's more complicated than you might think. Nothing wrong with the green, just change it every couple of years. Supposedly the Red is less toxic than the green, for whatever that is worth, I don't think any of us is planning on tasting the stuff. Just my 2 bits. PJ
PJ Jennings

In the UK you should be using blue antifreeze in our engines. This has the silicate based and non OAT based stabiliser. Same as Bluecol used to be. Freely available in places iike Halfords in Autumn and Winter, usually hidden in some corner in Summer.
Dave H
Dave Hill

Thanks guys for the advice. I have been referred to a recent article in Practical Classics. They say "red, orange or pink OAT antifreeze is best avoided in classics". Apparently this is formulated for modern, sealed cooling systems and can gel if it is in frequent contact with air. I suspect the slime coating the internals of the TF's radiator and hoses was in fact OAT gel. Good thing is it was easily hosed away.

Jan T
J Targosz

Here in France, color does not mean anything.
In our car, we can find steel, cart iron, copper, bronze, brass for the drain tap and probably tin and lead for radiator and heater. Maybe others...

Antifreezing feature is probably not an issue for normal use.

But against corrosion, the best way is to read the manufacturer datasheet when available. Glysantin datasheet are available on the web. G 30 seems to be OK.

These datasheet shows corrosion test for different material.


LC Laurent31

Colour means nothing here
You can get OAT in green now as well as red just to confuse and yes OAT coolants need to be in a sealed system like modern cars with full pressure recovery tanks
Mitsubishi here has two coolants one blue and one green/blue which can't be mixed, -getting the right one for topups is a bit of a problem after the colour goes off a bit, they sort of look the same
I would suggest for a T type a non OAT coolant would be better but don't forget to change it every couple of years or it will do more damage than plain water
William Revit

In a country where "antifreeze" performs the function that the very name imparts, ie: against freezing: and for cars such as my own TF that languishes in an unheated garage for up to 6 months, and where temperatures can drop to -40°C , the colour has absolutely nothing to do with protection and I'm surprised to see that this is an issue.

Protection for us, means a solution of (mainly) Ethylene Glycol in about 50% concentration. The most popular product is Honeywell "Prestone" which happens to be yellow. Other less popular brands can be any colour.

However, a word of caution about using antifreezes that are formulated for modern cars, many of which now have aluminium radiators. Formulations like Dex-Cool for these applications, contain organic acids which reacts differently with the older copper/brass radiators, such as our T-Series use. In a warm or even hot climate, chemical reaction from organic acids can be even quicker. So keep away from this stuff.

Traditional Ethylene Glycol-based antifreezes are ideally suited for our MGs and contain rust and corrosion inhibitors as well as silicate compounds to minimize the formation of acids, but no organic acids to eat away at our radiators.

BTW, can somebody please tell me the meaning of 'OAT'.

Gord Clark
Rockburn, Qué.
Gord Clark

Sorry to have confused readers by mentioning "red antifreeze. In the UK this generally refers to Organic Acid Technology (OAT) and Ethelene Glycol based coolant is generally blue (Bluecol) or green. It appears colours vary in outside the UK. I understand Glycol is the stuff for unsealed cooling systems.

Jan T
J Targosz

This thread was discussed between 22/07/2017 and 24/07/2017

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