Anti Freeze

[J.C.]

Am about to flush my radiator and put some anti freeze in, any advice on which type of anti freeze to put in would be gratefully received.

[jerrytr5]

Whatever was in it before, probably blue.

Jerry

[North London Mike]

JC

This is what I use (legal disclaimer: not a recommendation). Our old cars need BLUE coolant/ antifreeze. New cars/ modern use PINK antifreeze

[RobH]

Don't just go by the colour as that can be misleading.  If it says OAT or HOAT (organic acid technology)- usually red or orange-  it is the wrong stuff.  TRs need inorganic additives (IAT) also called silicate, which is usually, but not always, blue - sometimes it is green or even yellow depending on the make. 

 

[Mike C]

2 hours ago, RobH said:

Don't just go by the colour as that can be misleading.  If it says OAT or HOAT (organic acid technology)- usually red or orange-  it is the wrong stuff.  TRs need inorganic additives (IAT) also called silicate, which is usually, but not always, blue - sometimes it is green or even yellow depending on the make. 

 

I agree. There is no standard that specifies a colour against a performance requirement. Mazda,for example , sell the same coolant , dyed in different  colours for different geographical markets.

I use Penrite OEM coolant at 50% concentration, which is to ASTM D-3306. This product  happens to be  green.

Way, way back I used Castrol anti  freeze type P, whatever that was. It was also green.

Back when TR6's were made, the coolant specification was not the science it is today. The Brown Book just recommends clean, soft water with added anti freeze if required.

Edited December 4, 2024 by Mike C

[J.C.]

Appreciate all the helpful advice given, the last thing I want to do is put the wrong spec anti freeze in and cause a problem. 

Have ordered 5 litres of Millers Blue Alpine Anti Freeze IAT. 

[charlie74]

What would happen if you put (H)OAT in a 6 cooling system?

[PodOne]

Put 50% red in mine simply because I had it on the shelf which I use for our VW/Honda and lasts 5 years between changes. She seems to run cooler than on the Blue at 50%.

Out of interest why blue over red?

Andy 

[jerrytr5]

How does such a simple question morph into such a long thread !

You can put any type of antifreeze in, but if you change types it must be fully flushed. Mixing the types creates a jelly, not a coolant.

I'm sure we'll have a chemist along in a minute to explain why.

Jerry

[RobH]

52 minutes ago, PodOne said:

Out of interest why blue over red?

OAT antifreeze was formulated to have the right anti-corrosion additives for modern cars - compatible with the materials used in modern aluminium engines and radiators.  Unfortunately those additives seem to attack some of the mix of materials used in older engines and cooling systems. This from the FBHVC:  

https://www.fbhvc.co.uk/coolant

[Mike C]

Does the UK have a standard colour coding to reflect the different coolant technologies? No where else does.

[Andy Moltu]

No.

Blue generally non OAT.

Green variable.

Red & yellow non OAT but not universal.

Not all of the Non-OAT are bad and the likes of Prestone can be used. However mixing the two types can cause gelling so it's vital to fully drain and flush first if changing. 

[Mike C]

i thought so. It's a real trap , buying coolant on colour alone, and one that many people fall into.

You have to check the product tech data sheets.

[Tom Fremont]

God bless our all iron engines, and no aluminium radiator will ever occupy the engine bays of my TRs! If there's any reason why any anti-freeze poses a hazard to these engines I'd like to know why.

For those who might not know, ethylene glycol requires 4X the flow rate of water to carry away an equal amount of heat. So any more than necessary in the mixture degrades the cooling capacity.

[Bill944T]

So any more than necessary in the mixture degrades the cooling capacity.

 

And, there is a percentage dilution where the “neater” the mixture, the higher the temperature it freezes..

I haven’t explained that very well… say you mix at 50%, it won’t freeze until say -30 C but if neat, it’ll freeze at say -15 C.

Regards

Bill 

[stuart]

FWIW I have red in my 4a but its a Caterpillar version used in likes of D9/D10 bulldozers (Dont ask I have a source). Works fine.

Stuart.