Antifreeze is antifreeze - not any more

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Shifty1962

Well-Known Member
Posts
4,209
Location
The Winchester Club - Englandshire
Can somebody explain why early TD5 engines use normal Ethylene Glycol and later ones the OAT stuff? Apparently they should not be mixed or used in the wrong engine (ie. OAT should not be used in early TD5s and EG not in later TD5s). As far as I can tell the later TD5 engines are exactly the same engine with a few tweaks for emmisions and head failures due to cracks/porosity.

Will it do any damage to a later TD5 (my nice new shiny one) to use EG as I have 25 litres of the stuff in my shed? I used it in my old engine with no apprent problems other than it going bang which was nothing to do with antifreeze. Also when I stripped it down the cooling galleries looked just fine to me.

The man in my local motor factors says that EG antifreeze eats away at the aluminium parts over time causing a black sludge to form in the cooling system. However I once owned a V12 Jag with an all ally engine that used neat EG as recommended by Jaguar ????? And the early TD5s still have ally heads and ancillaries with coolant flowing through them ???

And just to rub it in the OAT stuff just happens to be dearer than EG and comes ready mixed so I'd be buying water as well as antifreeze. Anybody know where I could get it neat and mix it myself?
 
My Disco II needed the OAT stuff and I remember buying it neat. I can't remember whether I got it in Halfrauds or a small local motor factor though.
 
Ethylene Glycol is meant to rot alluminium heads. OAT is meant to be safe with ally. It's strange that early ones are meant to be able to use normal antifreeze though.
Ed Zackery. I dont believe they changed the composition of the aluminium alloy used for the later engines so I was wondering if its all just to get you to buy the dearer stuff?

Of course I dont want to knacker my engine for the sake of a few quid but with work thin on the ground every penny counts.
 
Ed Zackery. I dont believe they changed the composition of the aluminium alloy used for the later engines so I was wondering if its all just to get you to buy the dearer stuff?

Of course I dont want to knacker my engine for the sake of a few quid but with work thin on the ground every penny counts.

I used OAT in mine up until the waterpump and power steering pump fecked up just before christmas. I have normal anitfreeze in it at the moment. I will be going back to OAT again when I have the money to buy some more.:eek:
 
this evenings training session................

LEARNING ZONE

Antifreeze


Antifreeze works on the principle that the addition of an impurity to water lowers the freezing point and raises the boiling point.

Many years ago antifreeze was only added to the cooling system at the onset of winter. Protecting an engine from freezing is only one of the functions of a modern antifreeze. It also plays a major part in improving the ability of the water to cool the engine by increasing heat transfer.

It has important anti-foaming properties. Fast-revving engines may cause the coolant to foam and excessive foaming allows the formation of air pockets – which, in turn, result in poor cooling. The bubbles generated by the rapid spinning of the water pump impeller cause cavitation. This is a condition caused by the collapsing vapour bubbles in coolant on the surface of the metal which result in high shock pressure. The shock waves cause development of the small pinholes in metal surfaces such as the water pump impeller or the walls of a wet cylinder liner – which could reach as far as the cylinder itself. This isn’t a long term problem, it happens quite quickly. Two ambulances recently inspected in Scotland running on a 23 per cent antifreeze mix had both seized the engines because the brass water pump impellers had been eaten away by cavitation.

Another major function is corrosion prevention inside the engine and radiator as engines are full of electrochemically incompatible metals – cast iron, aluminium, copper, lead solder etc. Aluminium alloy engines are particularly vulnerable to corrosion.

One to the first antifreeze substances used was methanol, in the 1930s and continued to be used in cheaper antifreezes for a long time, but it was too volatile and evaporated relatively quickly. From around 1937 ethylene glycol solutions were favoured. This was a good anti-freezing agent, but, on its own, was really corrosive. Hence the addition of corrosion inhibiting additives. Much later BS 580 was introduced to make sure methanol based antifreezes and sub-standard corrosion prevention additive packages were not available.

Over the past few years the additive packages used in antifreeze have become more critical because of smaller cooling system volumes, higher temperatures, higher pressures and greater use of alloys. Smaller systems are heavily loaded and are not as forgiving as the older, higher capacity cooling systems. On top of that vehicle manufacturers are specifying longer service intervals.

The fundamental ingredient of antifreeze – glycol – has not changed very much, but the additive packages certainly have. The vast majority of car manufacturers now use Organic Acid Technology (OAT) inhibitor packages which can be used in a base of MEG (Mono-Ethylene Glycol) or the less toxic MPG (Mono-Propylene Glycol).

The terms G11, G12 and G12+ are classifications of antifreeze developed by the VW Group, made by BASF, but seem to have gained universal acceptance.

The traditional antifreezes are generally classed as G11 – usually blue, green or yellow. These contain phosphate, nitrate, nitrite and silicate-based additives. They are used in a base of mono-ethylene glycol which is the toxic stuff.

Mono-ethylene glycol (MEG) has a density of 1.110 and registers on a standard issue tester/hydrometer. It is also the basis for many of the OAT antifreezes which vary in colour from florescent yellow to red, and are classed as G12. BUT Toyota use a red non-OAT antifreeze and the MG Rover SV uses green/yellow OAT – so you certainly can’t rely on the colour to tell you which sort of antifreeze is being used in a particular engine. Japanese antifreeze is phosphate based with an OAT package.

Silicate levels in G11 antifreezes vary. The level used to be as high as 1000 ppm, but this has been reduced to around 250 ppm. At this level there shouldn’t be any precipitation of silicates if mixed with another type of antifreeze. You may have heard of, or seen, cases of horrible green/yellow gel/sludge in the radiator if different types of antifreeze are mixed. BMW still favour a conventional high silicone green anti-freeze.

G12+ is another OAT based antifreeze, purple in colour, but this can be mixed with G11 or G12 without causing any problems.

Antifreezes needed to become less toxic and mono-propylene glycol (MPG) is now used by some car manufacturers, such as Fiat – and it’s compulsory in Switzerland, mixed with the G12 or G12+ additive package. MPG has a density of 1.033 and although it might register on your ordinary antifreeze tester, the figures won’t be right. Accurate measurement needs a refractometer.

MPG and MEG are compatible and mixing won’t cause any problems – in fact they are used together for use in the Arctic.

Most vehicle manufacturers specify a 50:50 mix of water to antifreeze. The principle of an impurity lowering the freezing point is limited. The minimum freezing point achievable by this method is around -50ºC and occurs at 60 or 70 per cent concentration. Above this concentration it will not lower the freezing point further and at 90 per cent antifreeze concentration the solution will begin to freeze at only -20ºC (it doesn’t form proper ice – it’s more like a nasty thick sludge). Corrosion and cavitation prevention need the 50:50 mix.

A combustion gas leak (resulting from head gasket failure) will deplete the corrosion inhibitors as the carbon dioxide dissolves in the coolant and forms carbonic acid.

Now the risk of silicate precipitation has been reduced there is still an issue with different corrosion inhibitor packages which can work against each other.

If you check a car which has an unclear service history, you’ll have no idea what is already in the cooling system. It could have been topped up a dozen times with different antifreezes so to avoid the possibility of production of the gel it is safest to use a G12+ antifreeze such as Comma Extreme Red. This is a very bland/non-reactive mix and shouldn’t cause any problems.
 
this evenings training session................

LEARNING ZONE

Antifreeze


Antifreeze works on the principle that the addition of an impurity to water lowers the freezing point and raises the boiling point.

Many years ago antifreeze was only added to the cooling system at the onset of winter. Protecting an engine from freezing is only one of the functions of a modern antifreeze. It also plays a major part in improving the ability of the water to cool the engine by increasing heat transfer.

It has important anti-foaming properties. Fast-revving engines may cause the coolant to foam and excessive foaming allows the formation of air pockets – which, in turn, result in poor cooling. The bubbles generated by the rapid spinning of the water pump impeller cause cavitation. This is a condition caused by the collapsing vapour bubbles in coolant on the surface of the metal which result in high shock pressure. The shock waves cause development of the small pinholes in metal surfaces such as the water pump impeller or the walls of a wet cylinder liner – which could reach as far as the cylinder itself. This isn’t a long term problem, it happens quite quickly. Two ambulances recently inspected in Scotland running on a 23 per cent antifreeze mix had both seized the engines because the brass water pump impellers had been eaten away by cavitation.

Another major function is corrosion prevention inside the engine and radiator as engines are full of electrochemically incompatible metals – cast iron, aluminium, copper, lead solder etc. Aluminium alloy engines are particularly vulnerable to corrosion.

One to the first antifreeze substances used was methanol, in the 1930s and continued to be used in cheaper antifreezes for a long time, but it was too volatile and evaporated relatively quickly. From around 1937 ethylene glycol solutions were favoured. This was a good anti-freezing agent, but, on its own, was really corrosive. Hence the addition of corrosion inhibiting additives. Much later BS 580 was introduced to make sure methanol based antifreezes and sub-standard corrosion prevention additive packages were not available.

Over the past few years the additive packages used in antifreeze have become more critical because of smaller cooling system volumes, higher temperatures, higher pressures and greater use of alloys. Smaller systems are heavily loaded and are not as forgiving as the older, higher capacity cooling systems. On top of that vehicle manufacturers are specifying longer service intervals.

The fundamental ingredient of antifreeze – glycol – has not changed very much, but the additive packages certainly have. The vast majority of car manufacturers now use Organic Acid Technology (OAT) inhibitor packages which can be used in a base of MEG (Mono-Ethylene Glycol) or the less toxic MPG (Mono-Propylene Glycol).

The terms G11, G12 and G12+ are classifications of antifreeze developed by the VW Group, made by BASF, but seem to have gained universal acceptance.

The traditional antifreezes are generally classed as G11 – usually blue, green or yellow. These contain phosphate, nitrate, nitrite and silicate-based additives. They are used in a base of mono-ethylene glycol which is the toxic stuff.

Mono-ethylene glycol (MEG) has a density of 1.110 and registers on a standard issue tester/hydrometer. It is also the basis for many of the OAT antifreezes which vary in colour from florescent yellow to red, and are classed as G12. BUT Toyota use a red non-OAT antifreeze and the MG Rover SV uses green/yellow OAT – so you certainly can’t rely on the colour to tell you which sort of antifreeze is being used in a particular engine. Japanese antifreeze is phosphate based with an OAT package.

Silicate levels in G11 antifreezes vary. The level used to be as high as 1000 ppm, but this has been reduced to around 250 ppm. At this level there shouldn’t be any precipitation of silicates if mixed with another type of antifreeze. You may have heard of, or seen, cases of horrible green/yellow gel/sludge in the radiator if different types of antifreeze are mixed. BMW still favour a conventional high silicone green anti-freeze.

G12+ is another OAT based antifreeze, purple in colour, but this can be mixed with G11 or G12 without causing any problems.

Antifreezes needed to become less toxic and mono-propylene glycol (MPG) is now used by some car manufacturers, such as Fiat – and it’s compulsory in Switzerland, mixed with the G12 or G12+ additive package. MPG has a density of 1.033 and although it might register on your ordinary antifreeze tester, the figures won’t be right. Accurate measurement needs a refractometer.

MPG and MEG are compatible and mixing won’t cause any problems – in fact they are used together for use in the Arctic.

Most vehicle manufacturers specify a 50:50 mix of water to antifreeze. The principle of an impurity lowering the freezing point is limited. The minimum freezing point achievable by this method is around -50ºC and occurs at 60 or 70 per cent concentration. Above this concentration it will not lower the freezing point further and at 90 per cent antifreeze concentration the solution will begin to freeze at only -20ºC (it doesn’t form proper ice – it’s more like a nasty thick sludge). Corrosion and cavitation prevention need the 50:50 mix.

A combustion gas leak (resulting from head gasket failure) will deplete the corrosion inhibitors as the carbon dioxide dissolves in the coolant and forms carbonic acid.

Now the risk of silicate precipitation has been reduced there is still an issue with different corrosion inhibitor packages which can work against each other.

If you check a car which has an unclear service history, you’ll have no idea what is already in the cooling system. It could have been topped up a dozen times with different antifreezes so to avoid the possibility of production of the gel it is safest to use a G12+ antifreeze such as Comma Extreme Red. This is a very bland/non-reactive mix and shouldn’t cause any problems.


So in short, why do the early and later type TD5 engines use different types of anti-freeze?:confused::eek:
 
OK so while we are on the subject I have a slight problem, I was unsure what if any antifreeze was in my truck so I drained the rad and filled with some yellow/green floro stuff. (this by way of a stop gap)While doing this I noticed that the rad internals looked really gummed up with some deposit. Last week towing a caravan on a motorway the truck started overheating and the rad developed a small leak, got over that by careful driving.

Have now purchased a recon rad but before I fit it I want to flush the system to clean suspected deposits in engine and heater, for this job I bought holts speedflush. At the same time I bought 15ltr of bluecol (I live in france so buy in bulk when I can)

Will this be suitable for a 200tdi? never had any trouble with my V8's with bluecol but you have now sown a seed of doubt

Cheers
 
Its neat. Just needs to be mixed 50/50 with distilled water.
That means I've got loads of the stuff which should see me alright for a few years.
Apparently the trend is towards premixed so you cant fook it up.
I cant see the problem myself.
 
Its neat. Just needs to be mixed 50/50 with distilled water.
That means I've got loads of the stuff which should see me alright for a few years.
Apparently the trend is towards premixed so you cant fook it up.
I cant see the problem myself.

50:50 is a really hard ratio for the average chav to work out with only 10 fingers. (12 if yer a yam yam);):p:p:p
 
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