Coolant & Antifreeze Explained

oilman

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Coolant and antifreeze is a topic we are asked about on a regular basis, and often causes confusion; types, colours, service life etc.

Perhaps the most frequent cause of confusion is what the difference between anti-freeze or coolant is. Basically, they’re the same product (although the term “coolant” could just be applied to plain water; see below!)

To help clear some of the confusion up on the more technical details of antifreeze and coolants we enlisted the help of Martyn Mann – Technical Director, Millers Oils UK - who has provided the information below.

Not all antifreeze / coolant is the same!

Coolant can be plain water; water is a very effective coolant but would not protect against sub freezing temperatures or protect against corrosion inside the engine. The use of antifreeze protects against both problems.

Antifreeze not only suppresses the freezing point of your engine coolant, but provides good corrosion protection and increases the boiling point during use.

Most commercial antifreeze formulations include a glycol (to suppress the freezing point and raise the boiling point), corrosion inhibiting compounds and a coloured dye (commonly orange, green, red, or blue fluorescent) to aid in identification. A 1:1 dilution with water is usually used, resulting in a freezing point in the range of minus 37 °C to minus 42 °C, depending on the formulation.

There are two basic types of coolant available today dependent on the corrosion inhibitors used:

·inorganic additive technology (IAT)
·organic additive technology (OAT)

Inorganic Additive Technology

This is the traditional coolant based on inorganic additives and is called inorganic additive technology (IAT). It is a tried and proven chemistry that provides a fast acting protective film. The additives deplete and the coolant needs to be drained and replenished every couple of years. This type can be used on all mixed metal engines with components including steel, cast iron, copper, brass, aluminium and solder without any detrimental effect.

Organic Acid Technology

The newer OAT coolants work differently than the older silicate based IAT coolants. Aluminium and ferrous metals form a surface-layer of corrosion in the presence of moisture, even with the little bit of moisture in the air. OAT coolants prevent this metal-oxide layer that protects the surface against this corrosion. Inherent with their design, the OAT coolants last longer than the older traditional IAT coolants. This category of antifreeze cannot be used in systems containing yellow metals.

A couple of questions and answers.

Why are coolants different colours?

Coolants/antifreezes are coloured so you can visually see them; colour intensity can be an indication of over dilution. The different colours are non specific to the different types of antifreeze. The manufacturer can dye the product any colour they want. The colour is no guide to the actual type of antifreeze type and the label should be read before use.

What is best for performance use?

It is always best to use the engine manufacturer’s advice. If engine contains yellow metals [copper and brass as in older vehicles] then the long life products based on organic technology should not be used. As a general rule, most modern engines require the long life organic antifreezes.

Is there any advantage to using concentrate over pre-mixed coolants?

None other than the user may want to use the pre-mixed product due to ease of handling or cost and visa versa.

Can concentrate and pre-mixed coolants be mixed?

A simple answer is that you can, however do not mix IAT and OAT antifreeze together.

So, there we go. Hopefully this information has been useful, if you have any further questions not covered here please ask and I will try to get the answer.

With thanks to Martyn Mann and Millers Oils.

Cheers

Guy and the Opie Oils team.
 

chizzel89

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What about using the modern long life anti-freeze in older engines like the OM605/606?

Also, how many times would you need to drain and fill the cooling system with fresh water (and run it for a bit) to get rid of the old ethylene glycol anti-freeze sufficiently?
 

coventryslk

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I have confusion of which i require for my thermostat change

ECP - blue cheapo IAT
GSF - Red OAT long life

merc says 310.0 approval in manual and original should last 15 years although long life is for 5 years and old type blue last for up to 2

I just want to get it right, merc wont give me part numbers so i looking for advice off here

I am sure i have the long life and want to know of a supplier rather than going to a dealer that has the correct stuff, sort of how Fuchs do the green wheel bearing grease a lot cheaper than the tube sold at dealers
 
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oilman

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Hi

Can you let me know the model and year? That way I can check on it.

Cheers

Tim
 

charlie002

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Water coolant level / check transmision oil

Mercedes 2000 E240 is the level of the water to be up to the clear part of the tank wich means it is about 70mm below the top?
How do you check the level of the transmission when the cap comes off there is no dipstick?
I would appreciate some advice on these items please
charlie002
 
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oilman

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Hi

Sorry, but I don't know those details, you need someone who is more familiar with that model.

Cheers

Tim
 

mersum1es

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Arzaam

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the mercedes original green coolant available at dealerships is it IAT or OAT? can IAT coolant be used in a w203 mercedes c180?
 

hotrodder

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the mercedes original green coolant available at dealerships is it IAT or OAT? can IAT coolant be used in a w203 mercedes c180?

The coolant MB supply is typically G48 or G05 both of which are HOAT. G48 can be green, blue or various bluey greens/greeny blues depending on brand. G05 is typically dyed yellow/amber.

If you click the Bevo link in the post above yours table 3 shows various coolant specs 325.x is concentrate, 326.x is pre mixed stuff
325.0 is the usual spec for passenger cars and the approved coolants are typically the aforementioned G48 and G05. A w203 would've been filled with one of these when new i believe, exact flavour and colour would depend on who MB were buying coolant from at the time...
325.5 is a newer spec and the approved coolants are typically G40 (Si-OAT)

http://www.glysantin.de/en/products.html lists the various different flavours, note that G48, G05 and G40 all contain silicates which are one of the IAT inhibitors hence them being HOAT (hybrids of OAT and IAT). The story goes that while long lasting OAT coolants aren't as good as IAT in areas subject to cavitation like water pumps. Not a big deal on many cars as the water pump is typically changed when the cambelt is due because if the waterpump lets go it can take the cambelt with it and ruin your day. Not an issue when the engine has a timing chain so MB spec a coolant with silicates and also stuff a packet of silica gel in the header tank to slowly leech silicates into the system

You can use a basic IAT coolant but it won't provide as much corrosion protection as one of the proper HOAT flavours and the change interval will also be shorter which, in the UK at least, typically makes it a false economy as something like Comma G48 is available pretty much anywhere for less money than the stealers want and not much more £ than a basic IAT coolant
 

Arzaam

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The coolant MB supply is typically G48 or G05 both of which are HOAT. G48 can be green, blue or various bluey greens/greeny blues depending on brand. G05 is typically dyed yellow/amber.

If you click the Bevo link in the post above yours table 3 shows various coolant specs 325.x is concentrate, 326.x is pre mixed stuff
325.0 is the usual spec for passenger cars and the approved coolants are typically the aforementioned G48 and G05. A w203 would've been filled with one of these when new i believe, exact flavour and colour would depend on who MB were buying coolant from at the time...
325.5 is a newer spec and the approved coolants are typically G40 (Si-OAT)

http://www.glysantin.de/en/products.html lists the various different flavours, note that G48, G05 and G40 all contain silicates which are one of the IAT inhibitors hence them being HOAT (hybrids of OAT and IAT). The story goes that while long lasting OAT coolants aren't as good as IAT in areas subject to cavitation like water pumps. Not a big deal on many cars as the water pump is typically changed when the cambelt is due because if the waterpump lets go it can take the cambelt with it and ruin your day. Not an issue when the engine has a timing chain so MB spec a coolant with silicates and also stuff a packet of silica gel in the header tank to slowly leech silicates into the system

You can use a basic IAT coolant but it won't provide as much corrosion protection as one of the proper HOAT flavours and the change interval will also be shorter which, in the UK at least, typically makes it a false economy as something like Comma G48 is available pretty much anywhere for less money than the stealers want and not much more £ than a basic IAT coolant

thanks a lot you cleared up so many things for me, i guess ill go with that the dealership is offering right now as genuine mercedes coolant concentrate form, and ill change it every two years just to be on safe side
btw currently car has yellowish coolant but due to a hose leak most of it was lost and it has a low percentage of coolant right now,
the little bit of yellow OAT coolant that remains in the heater core etc , that wouldn't couase anty issues mixing with the green one right? or should i do a thorough flush? theres no rust or corrosion at all in the moment its clear
 

hotrodder

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Personally i'd flush the system through as colour of coolant is pretty meaningless i.e. there's a good chance that what's in there currently is G05 but it might not be and the dealer is probably gonna sell you G48 which is currently dyed blue if bought from them i believe
 

TheMightySteelers

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Hi,

If you did didn't use authentic mercedes coolant, would it affect your warranty on the car? I have a 2011 c class and I am unsure whether or not just to pop to Halfords and get some or go to the dealer to buy some?
 
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oilman

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Hi

It depends on if the coolant used is MB approved. If it isn't, it could affect the warranty. Depending on how low the level is, it might be okay to add a little water to bring the level up.

Cheers

Tim
 

Katana

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Getting confused which coolant my 1987 500SEC would like. The current fluid (not changed for ages) is the orange coloured stuff.

I thought I would simply buy some MB coolant on Ebay but each trader I have asked has said their product is the blue orblue/green fluid.

Anyone know where I can get the right stuff please? Just topping her up for now.

Many thanks!
 
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oilman

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Katana

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Tim - You're a star!!!!!!!

Thnaks so much.
 

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What spec will be in my 2010 C350CDi Tim????

And how much goes in it??
 

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