Which antifreeze is better: 50/50 Premix or pure AF mixed with distilled water?

I would say a good distilled water with antifreeze should be fine.
But if you're going to flush it, you could look into the new waterless coolants. Haven't used them myself, but read a lot of good about them.

 

The problem is that you don't know exactly what is in the water Prestone, Peak, etc. add to make the premix. I use distilled water, but I have a lab distiller that I have used to make all my distilled water for the last 30 years. I use it for cooking, making coffee, adding to coolant for the cars and adding to the windshield washers (it's getting hard to find the concentrate - I have to research making my own). Most supermarkets also stock distilled water amongst the overpriced designer waters.

I'm skeptical about the claim that distilled water encourages corrosion. Tap water varies a lot around the country, where I live it's very caustic, Ph around 8, lots of heavy metals, arsenic, etc. You ought to see the junk I drain out of the residual tank in my distiller.

 

This thread: http://www.ferrarichat.com/forum/456-550-575/379604-how-hot-does-your-456-550-run-2.html has some interesting info on antifreeze, corrosion inhibitor, and different types of purified water.

The whole thread is interesting, but we had a water chemistry expert who chimed in on the last page to clarify some of the differences between water purified by distillation vs water purified by reverse osmosis.

 

Prestone's web site says their 50/50 premix uses demineralized water. I don't see a reason not to use it, and it is what I use in all my vehicles.

 

Peter, I think calling these things gauges is a stretch . Not only are they not marked sufficiently, even when they're on the marks, they can be off by 20 degrees. Heat indicator might be a better name for them as about the only thing they're good for is letting you know if the engine is cold, warm or HOT.

 

Well, yes; there are potential issues with distilled water if that's ALL you use. It isn't the fact that the water is distilled, demineralized, or sterilized. The problems are associated with not having any kind of antifreeze/coolant in the cooling system, no matter what kind of water you use.

Just because a car lives in a climate where the weather never gets below freezing, is no excuse to use pure water as a coolant.

As for price difference, it seems silly (to me anyway) to pay nearly the same price for two products, one of which is half water. I wouldn't worry about the quality of the water the manufacturers use. I doubt if it's any better (or worse) than the demineralized or distilled water you can buy at your local supermarket. Remember, you aren't injecting this into your brain; it's going into your cooling system.

Also consider this: If you flush your system from time to time, you are likely to flush it with water and most likely you'll do that several times. Owing to the fact that it's rather difficult to drain all the fluid from the cooling system, you'll have a certain (unknown) amount of water remaining. This water will be essentially free of anti-freeze. If you add a 50/50 mix you will end up with a system containing something less than a 50/50 mix, depending on how much flushing water is trapped.

On the other hand, if you have an 18L system and add 9L of coolant concentrate (pure anti-freeze) to a freshly flushed system and then top off with distilled water, you will have the desired 50/50 coolant mixture. You don't want to deviate too far from 50/50 in most cases.

But what about the trapped flushing water existing before you re-fill the system? It should be free of coolant but will be tap water unless you flush with distilled water. The best coolant concentrates which are formulated for aluminum cooling systems work well with ordinary tap water because they're specifically designed to protect against mineral deposits. Of course, the fewer minerals the better and if I lived in a hard water area, I might consider doing the last flush with distilled water.

But my local water isn't bad, so I add the correct amount of pure coolant and top off with distilled water when I change coolant. I don't worry about the small amount of trapped tap water because the coolant I use is specifically designed to cope with minerals found in tap water, even in aluminum systems.

That's my two cents. Take it for what it's worth.

 

I can't believe there is this much angst about this topic. In addition to using distilled water in a 50/50 mix the biggest thing you need to do is change the coolant regularly. Do those two things and you'll have no problems.

By the time a lot of people get these sort of cars they already over ten years old (probably a lot older than that) and they probably were left unused a lot during the winter so that the coolant sat uncirculated for long periods. It breaks down in stagnate areas like under hoses near a clamp then pockets of corrosion can develop.

So drive the damn cars, change your coolant and if you feel better paying more with the 50/50 premix blend go for it.

 

A lot of the angst probably stems from the possibility of getting it wrong and doing some serious damage to the engine's cooling system, including the cylinder liners, and facing a 5 figure repair bill.

Too, some people just can't find the time to drive the cars, but can't bear the thought of parting with them, so they become garage queens, so your point about stagnation and "dead legs" is well taken.

 

I'm going to belabor the point. Disregarding (for the moment) the issue of antifreeze mix, the basic discussion is the difference between Distilled Water (DW), reverse-osmosis water (RO) and tap water (TW). I'm not a chemist, but I'm actively involved in the computer controls for a large-scale municipal water treatment plant.

Tap water is filthy. the types of biological and mineral deposits in the water varies greatly, depending on where you live, and what the source of the water is, and how it is treated. Government mandated standards are a compromise, and are influenced by political and financial factors. Where I live the mineral deposits in the raw water are huge, so we treat the water with Ferric Chloride (FC), basically a molecule that attracts and holds most of the mineral molecules and Chlorine for the biologicals. The ferric chloride is filtered out of the water through a series of sand/Diatomaceous Earth filters. Ferric chloride is toxic, highly corrosive and acidic. The output from the filtration chain is monitored for pH to determine if all of the FC has been filtered out of the treated water. If the outflow is too acidic the filters are back flushed. The effluent that gets flushed out is truly nasty stuff.

If you use tap water you are depending on the diligence and competence of the people running the treatment plant.

Reverse osmosis (RO) is a water purification technology that uses a semipermeable membrane. This membrane-technology is not properly a filtration method. RO can remove many types of molecules and ions from solutions. The result is that the contaminants are retained on the pressurized side of the membrane and the pure water is allowed to pass to the other side. To be "selective," this membrane should not allow large molecules or ions through the pores (holes), but should allow smaller components of the solution (such as the water) to pass freely.

So RO removes "many types of molecules and ions," but not all. What is the output pH? Better than tap water, but I'd rather use distilled.

(From No-Rosion website):
"During the distillation process, water is vaporized into its gaseous phase, so all impurities are left behind. These impurities include a number of minerals, including calcium and magnesium, the two components of hardness. The water is then condensed back into its liquid phase, so the resulting liquid is pure water. In fact, some of the purest water on earth. The problem is that distillation strips impurities from water, resulting in water molecules that are electrochemically imbalanced. So distilled water will actually strip electrons from the metals in a cooling system as it attempts to rebalance itself electrochemically. This can result in damage to metals in a cooling system.

Using distilled water in combination with 50% antifreeze effectively cuts the amount of distilled water in half. By compounding with glycol, it will not cause damage to metals in a cooling system. For this reason, it is safe to use distilled water in a 50/50 mix."

I'm skeptical of this claim of "electrochemical imbalance." pH measures hydronium ion concentration, so if your pH is correct the ion concentration should be minimal. Absolute pure water has a pH of 6.81 at 37º C.

I also run the distillate directly form my distiller directly through an activated carbon filter to remove any aromatic hydrocarbons which may have vaporized at a lower temp than the water, and thus would remain in solution. A Honeywell Process Engineer suggested I do that.

Like I said, I'm not a chemist, but distillation is exactly the same process Mother Nature uses when she evaporates impure water from the oceans, then condenses it in the atmosphere and drops it upon us as rain. And Ferrari suggests using rainwater mixed with coolant in your radiator, which is good enough for me.

 

Exactly. if you dont like to mix, buy premixed and spend a tad more. If you want to save some $, buy concentrate (straight/pure ethylene glycol for rads, and heck- get your free distilled water by placing a clean pail under the drain tube of your home ac!!!! Pure enough!

 

Ah but then there's the acid rain issue to worry about ...

Now here's a somewhat off topic story about distilled water that may point towards what some were trying to get at. I bought an expensive steam iron years ago and just used distilled water in it. It failed and started leaking after only a year and a half. Well I was pissed so I decided to read the owner's manual. Have do that eventually right? They specifically said not to use distilled water but just tap water. So maybe the pure distilled water WO antifreeze would be a bad thing after all? I couldn't exactly add antifreeze to the steam iron ...

 

I agree about the acid rain, and don't even think of using the water out of your downspout after it has run over a couple of thousand sq. ft. of whatever kind of roof you have (asphalt composition shingles, anyone?).

I'm just guessing here, but maybe your iron depended on contaminant deposits to seal seams, like radiator stop-leak?

Another interesting point: if you take an absolutely clean glass beaker, fill it with distilled water and microwave it it will not boil... until it is jostled (like when the door is opened) then it will explode! I haven't tested this assertion.

 

Yes I've seen this. Has too have something to disturb the surface tension. Not just distilled water either. Drop something into an almost boiling pot of water like pasta and it can boil over immediately.

Could be correct on the steam iron? Very curious.

 

Its superheated water. heated above 100 deg C, with no "hot spots" to trigger the normal rolling boil activity. This is more likely in a microwave, as typically, you can get the contents to absorb heat from the microwaves, yet, the container can stay still cooler.

Top of stove- less likely, cuz the burner usually will always have "hot spots" which will trigger the boil. DI water vs distilled vs tap- very little difference with this phenomenon.

 

But it did happen to my wife- cooking pasta, like stattsoff said. BOOM. Almost got a bad burn. Pasta came out aldente as usual, fortunately, whew.

 

Picking this up, why should demineralized (deionized)water be better than distilled? Worth paying for? Distilled costs about the same as demineralized. There is no difference between the 2. Who told you that stuff?

 

Add slowly though ...
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