Best suited antifreeze for aluminium engines/cooling systems?

[Tikka]

Hi
It just gives the minimum protection levels of 33%, 50% and 60% mix. https://www.commaoil.com/passenger-vehicles/products/view/563

When my coolant was changed out with this fluid i was told by the garage that our climate did not call for the 50% mix. I did wonder if they were just being cheap.

 

[kschachn]

Hi
It just gives the minimum protection levels of 33%, 50% and 60% mix. https://www.commaoil.com/passenger-vehicles/products/view/563

When my coolant was changed out with this fluid i was told by the garage that our climate did not call for the 50% mix. I did wonder if they were just being cheap.

On the Toyota coolant I buy (and BMW blue for my old BMW) it has some sort of warning not to go below a 30% or so concentration. So I would guess the 33% is about there.

No they are not being cheap, more water is better for a lot of reasons if you don't need the freeze protection.

 

[atikovi]

the challenge may be to remove ALL of the old fluid. You may use several drain and fills with de-ionized water, but even that is expensive.

What expensive?

 

[Tikka]

On the Toyota coolant I buy (and BMW blue for my old BMW) it has some sort of warning not to go below a 30% or so concentration. So I would guess the 33% is about there.

No they are not being cheap, more water is better for a lot of reasons if you don't need the freeze protection.

Hi
Thank you.
It is good to read that my coolant strength is ok and will not give engine issues. The garage that did the coolant change are a mercedes specialist, hence the G48 they used.

 

[2EHA]

Hi
Thank you.
It is good to read that my coolant strength is ok and will not give engine issues. The garage that did the coolant change are a mercedes specialist, hence the G48 they used.

G05 used to be MB 325.0 Anticorrosion/antifreeze before it was completely replaced by G48

 

[willbur]

I do not know what the ratings on it are, but Hondas have aluminum engines and aluminum radiators, and Honda brand premixed is already mixed with de-ionized water at the proper ratio. And a new Honda with it is rated for 10 years or 100K miles before first drain and fill. Honda specifies to just drain and fill. Do not flush and contaminate the system with any fluid not containing de-ionized water. And because a drain and fill does not replace all the old fluid, from then on you have to do it every 5 years.

Kebabaluba, if you use it, unless the vehicle is a new dry system, the challenge may be to remove ALL of the old fluid. You may use several drain and fills with de-ionized water, but even that is expensive.

You can buy the Honda brand fluids from the online stores at a lower price than from a Honda dealer even when you include shipping. OEMPartSource.years com is one of the good ones.

That Honda coolant went 13 years in my Accord. It looked like it was installed yesterday when I drained it and components were deposit free and like new. Could have gone alot longer than 13 years. I asked myself- why am I doing this?

 

[kschachn]

Jim-
I think you mean distilled water, not deionized. I believe deionized water is corrosive(?) and is commonly used for professional cleaning purposes.

No, distilled and deionized water are functionally the same. Neither one is "corrosive", that is mostly a gross misunderstanding and a basis for popular Internet lore. Both will dissolve metals in systems where freshly distilled or deionized water is flowing over surfaces, but in a closed system both will quickly become saturated.

As always a basic understanding of chemistry helps but unfortunately the web is full of non-technical garbage. A solution of hydrogen chloride in water? Now that's corrosive.

 

[JimPghPA]

I do not have a PHD in Chemistry, but my understanding is as follows. Please feel free to correct me if I am wrong.

Deionized water is pure water like distilled, but additional care is taken in all that it contacts can not add any chemical even in a very minute quantity that may conduct electric current. In other words it is soooo pure of ions that it can not conduct electricity at all. And if it can not conduct electricity, then electrons can not flow through it, and thus metals in contact with it can not rust. And the antifreeze properties ( most likely due from carefully chosen additives ) further prevent any wearing away or corrosion of metals that the mix comes in contact with. There probably are several ways it could be made. Distilling with only using not conductive non metal equipment such as all glass, and maybe some rubber connection tubing, would be a good start. And you would have to be careful in the distilling that no, absolutely no contamination from the original not distilled water, or left behind products, were transferred into the steam leaving the boiler. A slight amount of salt or any other conductive chemical from the source remaining boiling water would be all it would take to contaminate the final product.

Honda does not want you to introduce ANY water into the system that may contain ions that may aid electron flow that may aid corrosion. This is why Honda specifies simple drain and fill only with Honda premixed antifreeze. That way fluids that may contain ions are NEVER introduced into the cooling system ( including distilled water, that may contain ions) and therefore electrons still can not flow, and corrosion still can not happen.

It might even be more involved that that to make deionized water, I do not know. For instance, the very few molecules of heavy water may have to be removed before it can be ion free. That I do not know. Again I do not have a PHD in chemistry. What I do know is that de-ionized water is free of ANY ions that can conduct electricity. Thus it can not provide electron flow to enable corrosion.

kschachn bring up an interesting point that pure deionized water would quickly take on additional chemicals from what it comes in contact with, and I would add that includes taking on metals from the system it contacts. However when it is part of a solution of an antifreeze that has chemicals in it that prevent such things from happening, then it may remain free of such contaminates that would provide the ions needed to provide electron flow that would enable corrosion to happen. In other words deionized water alone probably would not be enough to prevent corrosion. But the mix of deionized water and the antifreeze with its carefully chosen additives, remains free of ions, and corrosion can not happen.

Still, introducing any water that is not deionized into such a cooling system would contaminate the entire batch of coolant with ions that would enable conduction of electrons that then would allow corrosion to occur.

And of course there are a couple of reasons why a mix of water and antifreeze is chosen instead of pure antifreeze. Some are that water has better ability to transfer heat than antifreeze. And therefore the mix also has a better ability to transfer heat. And most antifreezes actually will have a lower freezing point temperature when mixed with some water, compared to that same antifreeze if it were pure with no water at all.

 

[madeej11]

I do not have a PHD in Chemistry, but my understanding is as follows. Please feel free to correct me if I am wrong.

Deionized water is pure water like distilled, but additional care is taken in all that it contacts can not add any chemical even in a very minute quantity that may conduct electric current. In other words it is soooo pure of ions that it can not conduct electricity at all. And if it can not conduct electricity, then electrons can not flow through it, and thus metals in contact with it can not rust. And the antifreeze properties ( most likely due from carefully chosen additives ) further prevent any wearing away or corrosion of metals that the mix comes in contact with. There probably are several ways it could be made. Distilling with only using not conductive non metal equipment such as all glass, and maybe some rubber connection tubing, would be a good start. And you would have to be careful in the distilling that no, absolutely no contamination from the original not distilled water, or left behind products, were transferred into the steam leaving the boiler. A slight amount of salt or any other conductive chemical from the source remaining boiling water would be all it would take to contaminate the final product.

Honda does not want you to introduce ANY water into the system that may contain ions that may aid electron flow that may aid corrosion. This is why Honda specifies simple drain and fill only with Honda premixed antifreeze. That way fluids that may contain ions are NEVER introduced into the cooling system ( including distilled water, that may contain ions) and therefore electrons still can not flow, and corrosion still can not happen.

It might even be more involved that that to make deionized water, I do not know. For instance, the very few molecules of heavy water may have to be removed before it can be ion free. That I do not know. Again I do not have a PHD in chemistry. What I do know is that de-ionized water is free of ANY ions that can conduct electricity. Thus it can not provide electron flow to enable corrosion.

kschachn bring up an interesting point that pure deionized water would quickly take on additional chemicals from what it comes in contact with, and I would add that includes taking on metals from the system it contacts. However when it is part of a solution of an antifreeze that has chemicals in it that prevent such things from happening, then it may remain free of such contaminates that would provide the ions needed to provide electron flow that would enable corrosion to happen. In other words deionized water alone probably would not be enough to prevent corrosion. But the mix of deionized water and the antifreeze with its carefully chosen additives, remains free of ions, and corrosion can not happen.

Still, introducing any water that is not deionized into such a cooling system would contaminate the entire batch of coolant with ions that would enable conduction of electrons that then would allow corrosion to occur.

And of course there are a couple of reasons why a mix of water and antifreeze is chosen instead of pure antifreeze. Some are that water has better ability to transfer heat than antifreeze. And therefore the mix also has a better ability to transfer heat. And most antifreezes actually will have a lower freezing point temperature when mixed with some water, compared to that same antifreeze if it were pure with no water at all.

Long explanation, talk about a roundabout way of explaining things.

 

[JimPghPA]

When you explain something and you tell something to someone who already knows it you either bore them or insult them, and sometimes both.

But when someone makes incorrect comments regarding chemistry, about something you have already said, then, at least for them, and maybe a few others, a more detailed explanation probably is in order.

 

[willbur]

I do not have a PHD in Chemistry, but my understanding is as follows. Please feel free to correct me if I am wrong.

Deionized water is pure water like distilled, but additional care is taken in all that it contacts can not add any chemical even in a very minute quantity that may conduct electric current. In other words it is soooo pure of ions that it can not conduct electricity at all. And if it can not conduct electricity, then electrons can not flow through it, and thus metals in contact with it can not rust. And the antifreeze properties ( most likely due from carefully chosen additives ) further prevent any wearing away or corrosion of metals that the mix comes in contact with. There probably are several ways it could be made. Distilling with only using not conductive non metal equipment such as all glass, and maybe some rubber connection tubing, would be a good start. And you would have to be careful in the distilling that no, absolutely no contamination from the original not distilled water, or left behind products, were transferred into the steam leaving the boiler. A slight amount of salt or any other conductive chemical from the source remaining boiling water would be all it would take to contaminate the final product.

Honda does not want you to introduce ANY water into the system that may contain ions that may aid electron flow that may aid corrosion. This is why Honda specifies simple drain and fill only with Honda premixed antifreeze. That way fluids that may contain ions are NEVER introduced into the cooling system ( including distilled water, that may contain ions) and therefore electrons still can not flow, and corrosion still can not happen.

It might even be more involved that that to make deionized water, I do not know. For instance, the very few molecules of heavy water may have to be removed before it can be ion free. That I do not know. Again I do not have a PHD in chemistry. What I do know is that de-ionized water is free of ANY ions that can conduct electricity. Thus it can not provide electron flow to enable corrosion.

kschachn bring up an interesting point that pure deionized water would quickly take on additional chemicals from what it comes in contact with, and I would add that includes taking on metals from the system it contacts. However when it is part of a solution of an antifreeze that has chemicals in it that prevent such things from happening, then it may remain free of such contaminates that would provide the ions needed to provide electron flow that would enable corrosion to happen. In other words deionized water alone probably would not be enough to prevent corrosion. But the mix of deionized water and the antifreeze with its carefully chosen additives, remains free of ions, and corrosion can not happen.

Still, introducing any water that is not deionized into such a cooling system would contaminate the entire batch of coolant with ions that would enable conduction of electrons that then would allow corrosion to occur.

And of course there are a couple of reasons why a mix of water and antifreeze is chosen instead of pure antifreeze. Some are that water has better ability to transfer heat than antifreeze. And therefore the mix also has a better ability to transfer heat. And most antifreezes actually will have a lower freezing point temperature when mixed with some water, compared to that same antifreeze if it were pure with no water at all.

Thank you Jim-
However "experts" here fail l to explain why M-B (years ago) specified NOT to use distilled water in cooling systems because it is "hungry" for ions and would leach these from cooling system metals (corrosion). Perhaps this is no longer relevant because lead solder, etc is no longer used in todays cooling systems or the addition of additives prevents this? What chemistry was behind this recommendation? Would like to know.

Regarding de-ionized water as a cleaning agent, I was curious and found sites that mention this- perhaps this property is useful for that?

 

[Astro14]

Let's back up a bit...

Tap water, drinking water, has lots of dissolved salts in it. Salts in chemistry, by the way, aren't just sodium chloride, but a combination of a positive ions and negative ions. When dissolved in water, they can make an acid, a base, or be neutral. So, the salts in your water are a combination, calcium is common, but sodium and others are in drinking/tap water, really depends on the source, but water leaches those elements from the rock or aquifer from which its extracted.

Bottled water marketers, like Dasani, even add calcium carbonate, magnesium sulfate, and potassium bicarbonate for taste. They add salts, in other words.

If you have "hard" water in your town, or well, there are lots of dissolved salts. That's what causes build up of crust on your shower head or leaves "water spots" on your car when you wash it. The salts that are left when the water evaporates.

Pure water is just that: water with nothing else in it.

De-ionized water is regular water with ions removed. Pretty close to pure.

Distilled water is pure, nothing else was evaporated and distilled back in, so, pure.

De-ionized water and distilled water are used in labs to clean so that no salt residue is present after rinsing and drying lab equipment. It doesn't "clean" - that is remove dirt and soap - any better than regular water, but the point is after rinsing and drying, there will be no residue left on the equipment.

So, that's the background.

On to the claims that are made:

1. Mercedes specified not to use distilled. I hadn't heard this, and it's not in my service information for my Mercedes, which still recommends the use of distilled.

Got a source for that?

2. The reason for Mercedes change is the "hungry for ions" nature of distilled water "leaching ions" from the metal. OK, let's go back to 1. above. IF Mercedes changed their recommendation, when did they give this reason?

Got a source for that?

I can find lots of sites on the web making ridiculous claims, e.g. the Earth is flat, so, finding sites that claim something is hardly proof.

Before anyone can answer "what chemistry is behind this recommendation", I really want to validate that the recommendation is, in fact, true.

Because, in reading the posts you're making @willbur, it all looks like internet hearsay.

When you read Mercedes' specification for cooling systems, there is a MAXIMUM number of dissolved salts of various kinds. There is NO minimum amount of dissolved salts. The best way to get under that maximum, without extensive testing of your tap water? Use distilled or deionized water. Since there is NO minimum amount of dissolved salts recommended, a water with zero salts, like distilled, meets Mercedes' current specification.

Mercedes-Benz Betriebsstoff-Vorschriften

Die Mercedes-Benz Betriebsstoff-Vorschriften zeigen eine Übersicht der Anforderungen der im Fahrzeug benötigten Betriebsstoffe und der empfohlenen Produkte. Betriebsstoffe sind alle zum Betrieb eines Mercedes-Fahrzeugs / Aggregats erforderlichen Flüssigkeiten bzw. Schmiermittel z.B. Kraftstoff...

bevo.mercedes-benz.com

 

[kschachn]

Thank you Jim-
However "experts" here fail l to explain why M-B (years ago) specified NOT to use distilled water in cooling systems because it is "hungry" for ions and would leach these from cooling system metals (corrosion). Perhaps this is no longer relevant because lead solder, etc is no longer used in todays cooling systems or the addition of additives prevents this? What chemistry was behind this recommendation? Would like to know.

Regarding de-ionized water as a cleaning agent, I was curious and found sites that mention this- perhaps this property is useful for that?

What experts are posting here? What I see are some people responding to certain posts that are filled with half truths and Internet misconceptions.

Please post the exact Mercedes-Benz prohibition if you will. As has already been explained here, yes water will dissolve metals but in a closed system such as a cooling system the water will quickly become saturated. This is independent of what metal is in the system whether it be aluminum, iron, copper or lead. Beyond that there are passivation additives that help prevent corrosion but that's not due to the water being distilled or deionized. A coolant has a limited amount of chelation agents so why load them up with the water you're using to mix with the coolant?

If you are cleaning something critical you always use distilled or deionized water since it leaves no residue. There is zero functional difference between distilled or deionized but it is easier to produce deionized water since you don't need a distillation system only resin beds.

 

[kschachn]

Let's back up a bit...

Tap water, drinking water, has lots of dissolved salts in it. Salts in chemistry, by the way, aren't just sodium chloride, but a combination of a positive ions and negative ions. When dissolved in water, they can make an acid, a base, or be neutral. So, the salts in your water are a combination, calcium is common, but sodium and others are in drinking/tap water, really depends on the source, but water leaches those elements from the rock or aquifer from which its extracted.

Bottled water marketers, like Dasani, even add calcium carbonate, magnesium sulfate, and potassium bicarbonate for taste. They add salts, in other words.

If you have "hard" water in your town, or well, there are lots of dissolved salts. That's what causes build up of crust on your shower head or leaves "water spots" on your car when you wash it. The salts that are left when the water evaporates.

Pure water is just that: water with nothing else in it.

De-ionized water is regular water with ions removed. Pretty close to pure.

Distilled water is pure, nothing else was evaporated and distilled back in, so, pure.

De-ionized water and distilled water are used in labs to clean so that no salt residue is present after rinsing and drying lab equipment. It doesn't "clean" - that is remove dirt and soap - any better than regular water, but the point is after rinsing and drying, there will be no residue left on the equipment.

So, that's the background.

On to the claims that are made:

1. Mercedes specified not to use distilled. I hadn't heard this, and it's not in my service information for my Mercedes, which still recommends the use of distilled.

Got a source for that?

2. The reason for Mercedes change is the "hungry for ions" nature of distilled water "leaching ions" from the metal. OK, let's go back to 1. above. IF Mercedes changed their recommendation, when did they give this reason?

Got a source for that?

I can find lots of sites on the web making ridiculous claims, e.g. the Earth is flat, so, finding sites that claim something is hardly proof.

Before anyone can answer "what chemistry is behind this recommendation", I really want to validate that the recommendation is, in fact, true.

Because, in reading the posts you're making @willbur, it all looks like internet hearsay.

When you read Mercedes' specification for cooling systems, there is a MAXIMUM number of dissolved salts of various kinds. There is NO minimum amount of dissolved salts. The best way to get under that maximum, without extensive testing of your tap water? Use distilled or deionized water. Since there is NO minimum amount of dissolved salts recommended, a water with zero salts, like distilled, meets Mercedes' current specification.

Mercedes-Benz Betriebsstoff-Vorschriften

Die Mercedes-Benz Betriebsstoff-Vorschriften zeigen eine Übersicht der Anforderungen der im Fahrzeug benötigten Betriebsstoffe und der empfohlenen Produkte. Betriebsstoffe sind alle zum Betrieb eines Mercedes-Fahrzeugs / Aggregats erforderlichen Flüssigkeiten bzw. Schmiermittel z.B. Kraftstoff...

bevo.mercedes-benz.com

Thank you. The amount of just sheer nonsense revolving around this subject is truly incredible. It's not helped by the corresponding number of idiots on websites that have no clue of even basic chemistry yet make statements and definitive pronouncements as though they know what they are talking about.

 

[willbur]

Let's back up a bit...

Tap water, drinking water, has lots of dissolved salts in it. Salts in chemistry, by the way, aren't just sodium chloride, but a combination of a positive ions and negative ions. When dissolved in water, they can make an acid, a base, or be neutral. So, the salts in your water are a combination, calcium is common, but sodium and others are in drinking/tap water, really depends on the source, but water leaches those elements from the rock or aquifer from which its extracted.

Bottled water marketers, like Dasani, even add calcium carbonate, magnesium sulfate, and potassium bicarbonate for taste. They add salts, in other words.

If you have "hard" water in your town, or well, there are lots of dissolved salts. That's what causes build up of crust on your shower head or leaves "water spots" on your car when you wash it. The salts that are left when the water evaporates.

Pure water is just that: water with nothing else in it.

De-ionized water is regular water with ions removed. Pretty close to pure.

Distilled water is pure, nothing else was evaporated and distilled back in, so, pure.

De-ionized water and distilled water are used in labs to clean so that no salt residue is present after rinsing and drying lab equipment. It doesn't "clean" - that is remove dirt and soap - any better than regular water, but the point is after rinsing and drying, there will be no residue left on the equipment.

So, that's the background.

On to the claims that are made:

1. Mercedes specified not to use distilled. I hadn't heard this, and it's not in my service information for my Mercedes, which still recommends the use of distilled.

Got a source for that?

2. The reason for Mercedes change is the "hungry for ions" nature of distilled water "leaching ions" from the metal. OK, let's go back to 1. above. IF Mercedes changed their recommendation, when did they give this reason?

Got a source for that?

I can find lots of sites on the web making ridiculous claims, e.g. the Earth is flat, so, finding sites that claim something is hardly proof.

Before anyone can answer "what chemistry is behind this recommendation", I really want to validate that the recommendation is, in fact, true.

Because, in reading the posts you're making @willbur, it all looks like internet hearsay.

When you read Mercedes' specification for cooling systems, there is a MAXIMUM number of dissolved salts of various kinds. There is NO minimum amount of dissolved salts. The best way to get under that maximum, without extensive testing of your tap water? Use distilled or deionized water. Since there is NO minimum amount of dissolved salts recommended, a water with zero salts, like distilled, meets Mercedes' current specification.

Mercedes-Benz Betriebsstoff-Vorschriften

Die Mercedes-Benz Betriebsstoff-Vorschriften zeigen eine Übersicht der Anforderungen der im Fahrzeug benötigten Betriebsstoffe und der empfohlenen Produkte. Betriebsstoffe sind alle zum Betrieb eines Mercedes-Fahrzeugs / Aggregats erforderlichen Flüssigkeiten bzw. Schmiermittel z.B. Kraftstoff...

bevo.mercedes-benz.com

I read this many years ago (early 80s maybe). I did not keep the source bc I did not feel a need at the time to support my question on this forum 40 plus years in the future. The internet and this forum were not around yet. You got me there. Suffice it to say, I am confident in what I read and I had questions about that in a general sense about the chemistry till this day. Do you have M-B coolant recommendations going back that far? If so, lets see it
I posted this in the hope of finding out, not to go toe to toe with someone about it. I use distilled water in all my cars. Some how this question about the actual chemistry is elusive. Just want to know- Does distilled/deionized water leach metals out of coolant systems?
Regarding additives, I believe sebactate (sp?) is a component in many coolants and supposedly protects solder and metals from corrosion. So, possibly this indirectly supports the distilled water prohibition back then when it was not used in coolants ?
Regarding hearsay- alot of what is on this site is hearsay and one could say the same thing about this site and claims made on it that you do for finding sites that claim the earth is flat. Everyone has an opinion and can post it to find out what ppl know and get an answer to their question. Nothing wrong with that. I learned alot from Trav, for example, and look forward to his and maybe three others posting. Only reason I'm here.

 

[Astro14]

I posted straight up facts with a link to Mercedes‘ current, not old, recommendation.

If you want an old recommendation, in 1932, alcohol and distilled water were recommended.

Coolants have changed since then, but the chemistry of water, Ph, and salts has not.

The distilled water has been a constant in cooling system recommendations for several decades. If any manufacturer recommended against it, I would like to see where the manufacturer said that. A document, a website, whatever.

People may have stated that “Mercedes recommended“ but a lot of people say things that turn out to be false. I owned a 1981 Mercedes 240D. The owners manual said “distilled water” as the recommended mix for Mercedes Coolant. So did the manual for my 1992 300E. So does the manual to my 2005, so, again, distilled seems to be the constant here.

Lots of old wives’ tales, myths, and bad recommendations out there, and the challenge is figuring what’s true and what‘s garbage.

The internet has not made that determination any easier. So much bad information out there, on very popular YouTube channels, for instance.

But it has good made information more accessible, like the Mercedes Bevo site, which is updated by Mercedes regularly.

Of course, figuring out what is true and what isn’t, is complicated, and is perhaps impossible, if a person retreats into defensiveness, ego preservation, and ad hominem arguments.

Thats why BITOG prohibits those types of posts.

This site is to discuss and learn. Objective, professional discussion is welcome. Making the issue a matter of personal pride, or ego, or bickering, is not.

 

[willbur]

I posted straight up facts with a link to Mercedes‘ current, not old, recommendation.

If you want an old recommendation, in 1932, alcohol and distilled water were recommended.

Coolants have changed since then, but the chemistry of water, Ph, and salts has not.

The distilled water has been a constant in cooling system recommendations for several decades. If any manufacturer recommended against it, I would like to see where the manufacturer said that. A document, a website, whatever.

People may have stated that “Mercedes recommended“ but a lot of people say things that turn out to be false. I owned a 1981 Mercedes 240D. The owners manual said “distilled water” as the recommended mix for Mercedes Coolant. So did the manual for my 1992 300E. So does the manual to my 2005, so, again, distilled seems to be the constant here.

Lots of old wives’ tales, myths, and bad recommendations out there, and the challenge is figuring what’s true and what‘s garbage.

The internet has not made that determination any easier. So much bad information out there, on very popular YouTube channels, for instance.

But it has good made information more accessible, like the Mercedes Bevo site, which is updated by Mercedes regularly.

Of course, figuring out what is true and what isn’t, is complicated, and is perhaps impossible, if a person retreats into defensiveness, ego preservation, and ad hominem arguments.

Thats why BITOG prohibits those types of posts.

This site is to discuss and learn. Objective, professional discussion is welcome. Making the issue a matter of personal pride, or ego, or bickering, is not.

You're funny! I was speaking of 1980's not 1930's! Speaking of personal pride/ego-perhaps you should take your own advice...

Best I could find:

(2009) Article in the December "British Marque" p. 27 "Drain your coolant for winter"----

"Per a Mercedes-Benz tech publication 20-25 years ago...'Use tap water.....The one thing never to use is distilled water. Water likes to have a certain level of minerals (hardness) in it.....Distilled water is hungry for minerals and is very aggressive, taking the minerals out of the metals in your engine'."

"The author states that this is a controversial issue, but as a chemist he agrees with Mercedes-Benz."

There ya go Bro...

 

[Astro14]

I’m interested - but you’re asking me to accept, as fact, an opinion, a self-admitted controversial opinion, relayed from the author of an article in a car magazine, from 12 years ago, that refers to a tech publication that no one seems to be able to find?

Though I accept your quote as genuine, and believe that you found it as is, and while I appreciate the work, it‘s lacking the manufacturer recommendation I was seeking. I don’t know the author’s experience or credentials, so, it remains opinion.

If we could find the elusive “Mercedes tech publication” from 20-25 years prior to 2009, to which the author refers, and to which you’ve referred, that would be a good start.

If we could find something current, from a manufacturer, recommending against the use of distilled water, then, that would be even better.

I‘m willing to read, to listen, to change my mind, but it has to be because the facts are there.

 

[Astro14]

My memory is off. Out of curiosity, because I really do want to know the right answer, I downloaded a 1981 Mercedes W123 Owners Manual. It simply says “potable water quality” in the recommendation. So, it did not say distilled, or deionized, as I stated earlier.

Here’s the screenshot

 

[Astro14]

Now, I did have the service manuals for the car, and the OM 616, so, I might have been remembering the information from them, as the owners manual says, for top up, and not for mixing replacement.