R.O. water for coolant flush

[Snagglefoot]

The instructions on Prestone Dexcool ask for Soft Water. Again, this is just for Dexcool.

 

[kschachn]

Well distilled, deionized and RO water is certainly soft.

 

[zzyzzx]

Tap water is fine for this purpose, even if you happen to live in Flint Michigan.

 

[brianl703]

Tap water is fine for this purpose, even if you happen to live in Flint Michigan.

I wouldn't use tap water if you have to chip hard water deposits out of your toilet every few months (or buy toilet bowl cleaner in bulk at Costco...or both).

 

[zzyzzx]

I wouldn't use tap water if you have to chip hard water deposits out of your toilet every few months.

I've never had an issue using just tap water, even in vehicles I have kept for 25 years.

 

[brianl703]

I've never had an issue using just tap water, even in vehicles I have kept for 25 years.

Most tap water is probably OK.

The stuff here is something like 17 grains per gallon or 250ppm of hardness.

It's ridiculous. The bottom of my bathtub is covered in rust stains from (presumably) the iron in that water.

 

[BHopkins]

This is an absolute load of nonsense, and we've had discussions on here about it before. A classic case of someone having a tiny bit of knowledge and then extrapolating it into a mantra that is garbage.

Yes, metals will dissolve in distilled, deionized and RO water. And, those same metals will dissolve in tap water or soft water depending on the existing concentration. If there is low or no aluminum in the tap or soft water then exactly the same amount will be dissolved as in distilled water. Same for iron or any other metal. Water softeners do not remove aluminum but they do remove some iron, so this whole argument is silly.

The truth is however that this amount of metal is extremely small. We are talking about multi-kilograms of metal in an engine cooling system and micrograms of metal being dissolved. And not only that, since the system is closed once the water is saturated with the metal no more will dissolve. One would be hard pressed to think of a less technically significant issue than this. And on top of all this the coolant has passivation and anti-corrosion chemicals which help to prevent this in the first place, not that it is even significant.

Stupid and ignorant fear-mongering at its best. I wouldn't buy anything from those idiots just based on that crapola.

I can't speak about the potential of metals being drawn into the water with DI, RO, or distilled only water. But I can verify from personal experience, that ultra purified/polished water will attack metal components, to the point of destruction.

Many years ago I was managing an automotive seat belt test lab. It was a new facility, and the lab manager from a sister facility had a company design a water purification system. The purified water was used for salt fog testing, and also for the humidity generator on the environmental chamber. The water first went through a pair of sediment filters, then a charcoal filter. Next was a water softener, then a pair of DI tanks. Last was an RO system. From there, the water was used to make brine solution for the salt fog chamber, and also supplied water for the humidity generator.

Before long, we had problems with the electric heater elements failing in the humidity generator. When we replaced the heater elements, we found that the copper tube had been eaten through on the old heater element, resulting in the failure. This happened a few times before we called in an expert to help us.

The expert determined that our water was over polished, to the point that it was drawing metal from the components of the water generator system. The copper tubing on the heater elements was the softest metal, so it always got attacked first. We changed the piping, so the water for the humidity generator was sourced after the DI tanks, but before the RO system. This did the trick. We never had to replace another heater element.

Of course, this was not a closed system, like a cooling system on an engine. Instead, water was constantly consumed and replenished, to generate the humidity needed in the environmental chamber. But water can be too pure.

 

[kschachn]

Tap water is fine for this purpose, even if you happen to live in Flint Michigan.

Again it depends on the source. Surface water has lower hardness than well water. Here in our suburbs the hardness is above 20 grains.

Why load down the chelating agents in the coolant with that mess?

 

[willbur]

I can't speak about the potential of metals being drawn into the water with DI, RO, or distilled only water. But I can verify from personal experience, that ultra purified/polished water will attack metal components, to the point of destruction.

Many years ago I was managing an automotive seat belt test lab. It was a new facility, and the lab manager from a sister facility had a company design a water purification system. The purified water was used for salt fog testing, and also for the humidity generator on the environmental chamber. The water first went through a pair of sediment filters, then a charcoal filter. Next was a water softener, then a pair of DI tanks. Last was an RO system. From there, the water was used to make brine solution for the salt fog chamber, and also supplied water for the humidity generator.

Before long, we had problems with the electric heater elements failing in the humidity generator. When we replaced the heater elements, we found that the copper tube had been eaten through on the old heater element, resulting in the failure. This happened a few times before we called in an expert to help us.

The expert determined that our water was over polished, to the point that it was drawing metal from the components of the water generator system. The copper tubing on the heater elements was the softest metal, so it always got attacked first. We changed the piping, so the water for the humidity generator was sourced after the DI tanks, but before the RO system. This did the trick. We never had to replace another heater element.

Of course, this was not a closed system, like a cooling system on an engine. Instead, water was constantly consumed and replenished, to generate the humidity needed in the environmental chamber. But water can be too pure.

So...this brings up the old topic of using distilled water in automotive cooling system, eh Kschachn? LOL

 

[Warstud]

The instructions on Prestone Dexcool ask for Soft Water. Again, this is just for Dexcool.

View attachment 131806

I've never had an issue using just tap water, even in vehicles I have kept for 25 years.

Not all Tap Water is the same.

 

[Hall]

Not all Tap Water is the same.

Even "drinkable" water can mean a lot of different things. We only drink spring water and don't drink our tap water 😂 Our water is extremely hard and those minerals are something you don't want in a cooling system.

 

[Warstud]

This bottle of Zerex - 50/50 has DI water >>>>>>>>

 

[zrxkawboy]

Even if some forms of purified water are more aggressive, the coolant contains more than sufficient additives to prevent problems.

 

[MolaKule]

You don't think the chlorine and fluoride might interact with the coolant chemistry? Most times, about half the total coolant capacity is in the engine block. In a 10 quart system, you will have approximately 5 quarts of the chlorine/flouride water left to mix with the coolant. It's something I would not guess about (I'm not a chemist)..

Chlorine and Fluorine are in PPB or parts per billion, not parts per million or PPM, so I doubt there will be any corrosive effects.

 

[nthach]

Just look on any bottle of 50/50 coolant and it will probably say it contains Distilled Water

Deionized - which goes a step above distilled water. I believe an ion-exchange resin or an RO step is done before a steam distillation step is done with some systems.

Prestone states to use only distilled water to mix their concentrates. I recently switched a Lexus LS430 from Toyota pink to Prestone Cor-Guard, I did 2 water-only flushes followed by final coolant fill. Distilled was used for all of that. My local hippie grocery store only has RO water, I wasn’t feeling like a 20 minute drive just for DI water at a Whole Foods.

 

[nthach]

Even if some forms of purified water are more aggressive, the coolant contains more than sufficient additives to prevent problems.

Pure OAT coolants seem immune to hard water. pHOAT and old school green that uses phosphate and silicates benefit the most from distilled or DI water - you want the phosphates to “plate” and oasis ate the metals in the cooling system, not bind to metal ions(Ca/Mg/Na/Li) in hard water and drop out.

GM for years said a mix of Dex-Cool and “drinkable” water was all you needed. They did put into the owner’s manual for the Volt to use only a pre-mix of Dex-Cool and deionized water for the power electronics. With xEV inverters entering the mix, I’d want to run a factory pre-mix for the inverter loop.

Phosphates are seen as a very effective water softening chemical for that reason.

 

[Pablo]

DI, RO, Distilled, softened (NaCl or KCl), pure....whatever will work fine.

Hard mineral water, not so much

 

[sk_pete]

Tap water is fine for this purpose, even if you happen to live in Flint Michigan.

how much ppm, exactly ?
mine is 230....hot tap even more

Soft water 10–50 ppm
Slightly hard water 50–100 ppm
Hard water 100–200 ppm
Very hard water >200 ppm

 

[Pablo]

how much ppm, exactly ?
mine is 230....hot tap even more

Soft water 10–50 ppm
Slightly hard water 50–100 ppm
Hard water 100–200 ppm
Very hard water >200 ppm

Yeah I would say over 150 ppm or so.

 

[sk_pete]

i get chalky kettle (if not using ro). so i guess 150 is close.