Radiator--distilled or tap water?

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 agressive, taking the minerals out of the metals in your engine'."

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

Is water just water, or does it REALLY make a difference??

Aw crap I use distilled in the Midget...

I've heard you aren't suppose to use tap water in aluminium
radiators because it isn't good for the metal.

I'd use tap water. If you use antifreeze it will contaminate distilled water anyway so the purity factor goes out the window.

Either way you go, you have pluses and minuses. After the flap on the B forum I did a little checking on the topic to write an article for our local club. Depending upon where you live, tap water will be better. Here in the Northwest of the US we have really good tap water. If you are truly worried, buy the 50/50 premixed stuff. Bottom line is use IAT type anti-freeze and change it often.

I asked myself, "what is an 'IAT' coolant?"
and found this summary:

By Larry Carley
Technical Editor
Brake & Front End
April 01, 2007

All types of antifreeze contain corrosion-inhibiting chemicals to protect bare metal surfaces from electrolytic attack. Though automakers disagree on which chemical additives work best in their vehicles, essentially any kind of antifreeze will work in any vehicle. But how well will it protect the cooling system? And for how long? And will it void the OEM warranty? These are important questions that need to be answered.

There are essentially three basic types of antifreeze corrosion additives for passenger cars and light trucks:

“IAT” (Inorganic Acid Technology) is the traditional “green” formula antifreeze. This is the stuff General Motors used until 1996, Chrysler used until 2001, and Ford used until 2002 in its trucks and 2003 in its passenger cars. The green additive package contains phosphate and silicates, and provides good protection for cast iron and aluminum engine parts, as well as copper/brass radiators in older vehicles and aluminum radiators in newer vehicles. The corrosion-fighting chemicals are fast-acting, but wear out after two to three years or 36,000 miles of average use, so green coolant needs to be changed periodically to minimize the risk of corrosion damage.

“OAT” (Organic Acid Technology) is usually dyed orange to distinguish it from other types of antifreeze. In 1996, GM began using a new extended-life antifreeze, called “Dex-Cool.” The coolant contains a totally different kind of additive package called Organic Acid Technology (OAT). The OAT corrosion inhibitors are slower acting and provide protection over a longer period of time. OAT coolants typically have a service life of up to five years or 150,000 miles, making coolant changes less frequent, but still necessary (a fact that many motorists seem to forget).

Other applications that currently use OAT antifreeze as the factory-fill coolant include 1996-and-newer Audi, Jaguar, Porsche, Volkswagen and Land Rover, 2001-and-newer Saab, and 1996-and-newer Toyota, Nissan, Honda, Mazda and other Asian makes.

“HOAT” (Hybrid Organic Acid Technology) antifreeze is usually dyed yellow, but may also be dyed orange or green. HOAT coolants are currently used by Ford, Chrysler, Mercedes, BMW and Volvo. The additive package in a HOAT formula coolant also contains silicates for added aluminum protection. Most of the antifreezes in this category also meet the European “G-O5” specification for hybrid extended life coolant. The service life for HOAT is also five years or 150,000 miles.

UNIVERSAL COOLANTS?
Why not just have one “universal” coolant for all makes and models? Some antifreeze suppliers do sell a universal product. They claim it is fully compatible with all types of coolants and is safe to use in virtually any American, Asian or European vehicle application. Universal coolants are typically OAT or HOAT formulas that can go up to five years or 150,000 miles between changes when the coolant is used to replace another coolant or is added to a cooling system that already contains an OAT or HOAT coolant. But if used to top off a cooling system that already contains an IAT green formula coolant, the service life is the same as the original IAT green coolant (two to three years or 36,000 miles).

The issue with universal coolants is that a single formula cannot meet the conflicting OEM specifications for IAT, OAT and HOAT coolants. If a universal coolant contains silicates, it does not meet the OEM OAT specification. If it contains no silicates, it can’t meet the OEM HOAT specification. And if it contains phosphates or inorganic acid technology ingredients, it can’t meet the OEM OAT or HOAT specifications. Consequently, some antifreeze suppliers argue there is no such thing as a universal coolant because one formula cannot meet all the conflicting OEM specifications. This means distributors must offer three different coolants to meet the IAT, OAT and HOAT specifications — otherwise the coolant may not satisfy the OEM warranty requirements. That’s why the safest recommendation is to use the type of coolant specified by the vehicle manufacturer.

Of course, once a vehicle is out of warranty, motorists can use any type of coolant they want — and many do. Many people still prefer the traditional green formula coolant because it’s the least expensive, even if it requires a little more maintenance.

If a customer chooses a different type of coolant than that which was originally in the vehicle’s cooling system, the cooling system should be flushed to remove all of the old coolant. This will avoid any potential incompatibility issues between IAT, OAT and HOAT coolants. Their advice is to use “same with same.”

Collect Rain water in a clean can or something suitable, (Haynes 1980)

I use 50/50 from Farm & Fleet. Not much preference to any particular brand. Figure it will protect my car longer than I will need it.

Hmmm. I've been using distilled water for a long time now. Of course, I used tap water for a long time before that.

Seems the "aggressive" nature of distilled water would be rather tempered by the fact you are putting a slug of goop (what ever anti-freeze you choose) in it.

Similarly, I have seen the crud that builds up in my plumbing... you can't say that won't happen in my engine (and it certainly does, judging by the water passages when rebuilding).

Accelerated corrosion? Sure, maybe, how accelerated are we talking? A couple microns per drain and fill???

I vote distilled, it cost practically nothing, so why not. .50cents a gallon I believe at your grocery store

guaranteed to not have any minerals that can build up in your system

well...

the question was not "what do you use", and it was not "what is cheaper". the question was, "is there anything bad that distilled water can do to your engine?"

If distilled water is "hungry" for minerals and so will cause something bad to happen to your engine, I guess the next question ought to be: what kind of thing could it cause? Would your engine dissolve? I've never seen or heard of anything like that, from any cause.

But we have all seen corrosion (badly corroded aluminum can look like it was "dissolved" because in order for it to corrode fresh surface material must be exposed as the top surface is eroded away by some kind of friction, so the part gets smaller, compared to steel which swells 16 times and tends to open up fresh material as it does so, which is why steel rusts away just sitting there and aluminum gets white and fuzzy and then stops unless something is rubbing on it).

All antifreeze contains anti-corrosion ingredients, so if you are using anti-freeze (which you should, unless you are racing), then the distilled water question shouldn't be able to cause any kind of harm then, right?

Maybe those long ago pieces of advice from Mercedes ("20 - 25 years ago") were dealing with cars running only water in them, or antifreeze with low capability to control corrosion?

Rain water ("Haynes 1980") is essentially distilled water.

I think that the question is not whether adding antifreeze will make your water "impure anyway", but is whether, or rather, how much MINERAL contamination is safe to be in your cooling system.

As others already stated, some tap water is horribly contaminated with calcium, rust, sulfur, and so on, enough to be terrible in an engine. Tap water varies hugely around the country, and even from neighborhood to neighborhood, depending on the water source and the condition of the pipes, so no single answer is going to probably be true for everyone, when tap water is being discussed.

Also, engines have changed tremendously over the last 20 or 30 years, from mostly iron with one or two aluminum bits, to all aluminum with one or two iron bits, changing the anti-corrosion job that anti-freeze needs to do. Modern aluminum engines want some phosphates and silicates added to the coolant to help prevent corrosion (Porsche, VW and Toyota sell special coolants to make sure of this because not all coolants are made with it properly balanced per those mfr's liking).


Norm "intrigued, but unconvinced so still using distilled water at this point" Kerr

great article explaining all this

http://www.radiatorreporter.com/electrol.html

great article, but it talks about electrolysis caused by grounding issues created by electric devices with faults in their wiring.

The original poster was asking about distilled water and whether it, itself, can cause issues.
Still looking for some supporting information to understand if it would or not, and if so, what is best done to prevent it.

I would be willing to bet money that the people who manufacture coolant use distilled water to make it with...



Norm

- it seems that the electrolysis issue would be a bigger factor for aluminum radiators, than with our brass radiators as it erodes the aluminum by using it as an anode in the electrical circuit.
- based on the IAT/OAT chemistry and the make up of our engine cooling systems, IAT is what we want to use, not the new long life OAT stuff, and that Prestone is OAT although its labeling is poor and does not clearly say so on the outside!


I gleaned these two points from this:
Robert Kirk posted this over on the B Bboard about 12 days ago, and adds some more to our discussion:

My take is
A) follow OEm recommendatins which means IAT
B. OAT is taking over and probably has to do with higher Aluminum content in todays engines and radiators
C) I find no conclusive evidence modern OAT is actually bad for our cars...but I have only done a half dozen different word searches to the subject...I would like clear evidence that indeed OAT is bad for pre 80s LBCs....
From:
[www.arrowheadradiator.com]

The single most important factor that leads to radiator failure is lack of cooling system maintenance. The corrosion inhibitors in conventional antifreeze are gradually depleted over time, so the recommended coolant change interval has traditionally been every two years or 24,000 to 30,000 miles for preventative maintenance. The new long-life antifreeze formulas that can go 5 years or 100,000 miles between changes reduce the need for cooling system maintenance and can reduce the risk of premature radiator failure. But most vehicles still have antifreeze with conventional additives in their cooling systems. So when regular coolant changes are neglected, corrosion goes to work.

Aluminum is more vulnerable to electrolytic corrosion than either copper/brass or cast iron because aluminum is a highly reactive metal. When the corrosion inhibitors are used up and the pH of the coolant drops to 7 or below, aluminum becomes a sacrificial anode and is eaten away.

This same type of corrosion can also occur even when the coolant is in good condition if the engine does not have a good ground connection. Voltage from the charging system will flow through the coolant to ground, creating electrolysis corrosion that attacks the components in the cooling system.

Checking the pH of the coolant with chemically-treated test strips can help you determine if the coolant is overdue for a change. The alkalinity of a typical antifreeze/water mixture will vary depending on the additives in the antifreeze and the ratio of ingredients, but is usually somewhere between 8 and 11. The average for most antifreezes is around 10.5, but when diluted 50/50 with water and added to the cooling system the pH drops to the 8.5 to 9 range. Higher is not necessarily better, though, because some of the new long-life coolants have a pH of only 8.3. Staying power is what counts.

Traditional antifreeze formulas for domestic applications with aluminum radiators, cylinder heads or blocks contain a high level of silicates (which is not really needed in cast iron engines with copper/brass radiators). Silicates form a protective barrier on aluminum that protects the metal. The additives used in European and Asian OEM antifreezes, however, are different. The Europeans use less silicates and rely mostly on borates to inhibit corrosion. Their antifreeze also contains no phosphates because hard water can react with phosphates to form calcium and magnesium sediments. The Asians use phosphates but no borates and low or no silicates because they say borates may actually add to the aluminum corrosion problem if the coolant is neglected. The new long life coolants use an entirely different corrosion inhibiting chemistry that uses carboxylate organic acids instead of the silicates, phosphates or borates. Getting rid of the silicates, some say, helps extend the life of the water pump seal because the microscopic particles of silicate in conventional antifreeze are abrasive.

Regardless of what type of antifreeze you use, it should be meet OEM specifications and be "aluminum-safe" if the radiator is aluminum.


Also see:

[www.underhoodservice.com]


Regards,
Robert Kirk
563 323 1017
kirkbrit@yahoo.com
[www.kirks-auto.com]

I use Propelyne Glycol... the "food-safe" stuff.

VW believes phospates are the kiss of death to aluminum engines (hence their requirement is for the orange stuff that is phospate free).

The Propelyne has a lower thermal conductivity (draws heat out of the block and sheds it in the radiator slower) but it is a pretty low difference, plus I don't use 50/50 mix, more like a 60/40 of water to "coolant." This helps the conductivity and brings it back to slightly better than 50/50 Ethelyne glycol.

As far as water "liking" to have a certain level of minerals in it... perhaps, but I still think any additives will more than make up for any "inherent aggressiveness" of so-called pure water.

Oh, by the way, rainwater is naturally "soft" but it also tends to be acidic (which is definitely bad for your engine) and in some areas it can be as bad as pH 5! Rainwater also has a fairly high proportion of very small particles in it (soot, dust, bird poop, etc.) especially since rain drops form around "impurities" in the atmosphere.

Distilled for me but if I have to use the hose... so be it!