Any problem adding distilled water only to coolant reservoir?
 

I was just out in the garage adding some oil to my 8, and noticed that the coolant level in the reservoir was pretty close to the "L" mark. Anyone see any problem if I just top it off for now with distilled water only? I'm in L.A. where there's virtually no chance of freezing temperatures, and don't plan in being in freezing weather anytime soon, at least not before my next service trip to the dealer. Thanks for any input.

That's what I do. Just make sure you don't keep adding and adding it (as time goes on) unless you get a periodic coolant system flush, or before long your coolant:water ration will be all out of whack. Hope this helps!

Are you reading this with the engine warm? (Always take the readings with the engine fully warmed up.) If so, I don't see any particular problem with adding a little water--distilled or otherwise--but why do that if it is still above the "L" mark? Why not wait 'till you can get some coolant, mix it 50/50 with water, and add that mix to bring it up to the full mark. The purpose of the coolant is more than just preventing a freeze. The coolant-water mix has a higher boiling point than straight water and, therefore, allows the engine to run at a temperature higher than if straight water is used as the coolant.

But like I said, adding a small amount of water is not going to have a significant impact on cooling.

Buy a small bottle of 50/50 premix....top up as necessary. You can buy 2 L bottles were I live

Thanks, folks. The engine is cooled down at the moment and I don't plan to add water in perpetuity--I'm just too lazy to run out to Pep Boys or another store today and pick up some coolant. I'll have to go see Manny, Moe and Jack soon enough to get some oil. The level right now is virtually right on the "L" mark (I took another look with a flashlight), so I'll add a bit of distilled water just so I don't trigger a warning light.

NEVER use distilled water in a cooling system!

Distilled water is a much more corrosive liquid than regualr water because it is trying to replace all of the minerals that have been removed from the water by boiling. Hence it will corrode your cooling system, engine, and everything else that it touches.

Unless you live in a hard water area just use tap water. If you live in a hard water area then a bottled water might work for you.

Secondly, you must use coolant to both raise the boiling point as well as lower the freezing point so if you live in a hot area a mixture of anti-freeze and water is still necessary. Besides that, anti-freeze also has anti-corrosion chemicals to protect the metal of your engine as well as lubricants for your water pump. Always use anti-freeze

From How Stuff Works. com:

Fluid
Cars operate in a wide variety of temperatures, from well below freezing to well over 100 F (38 C). So whatever fluid is used to cool the engine has to have a very low freezing point, a high boiling point, and it has to have the capacity to hold a lot of heat.
Water is one of the most effective fluids for holding heat, but water freezes at too high a temperature to be used in car engines. The fluid that most cars use is a mixture of water and ethylene glycol (C2H6O2), also known as antifreeze. By adding ethylene glycol to water, the boiling and freezing points are improved significantly.

[the below table didn't paste well so here's the link:

http://auto.howstuffworks.com/cooling-system3.htm

]

Pure Water 50/50
C2H6O2/Water 70/30
C2H6O2/Water
Freezing Point 0 C / 32 F -37 C / -35 F -55 C / -67 F
Boiling Point 100 C / 212 F 106 C / 223 F 113 C / 235 F


The temperature of the coolant can sometimes reach 250 to 275 F (121 to 135 C). Even with ethylene glycol added, these temperatures would boil the coolant, so something additional must be done to raise its boiling point.

The cooling system uses pressure to further raise the boiling point of the coolant. Just as the boiling temperature of water is higher in a pressure cooker, the boiling temperature of coolant is higher if you pressurize the system. Most cars have a pressure limit of 14 to 15 pounds per square inch (psi), which raises the boiling point another 45 F (25 C) so the coolant can withstand the high temperatures.

Antifreeze also contains additives to resist corrosion.

Thanks for your concern and the link you provided. However, I think you're going to get a LOT of disagreement about the use of distilled water in the cooling system. Virtually every auto expert that I'm aware of (or that I can find with a Google search) recommends distilled versus tap water because the mineral contaminants in tap water, even highly-softened tap water, can build up in the cooling system over time. I recognize there's a school of thought that notes "leaching" of certain metals can occur with distilled water (and deionized water, for that matter, even to a greater degree) because they are seeking, so to speak, the minerals that have been removed from them. So, there may be no perfect solution. However, engine coolant itself is highly corrosive--that's why it generally contains additives to counteract corrosion, and those same additives presumably help fight corrosion when combined in a mix with distilled water.

Also, I just took a look at my owners' manual (which I really should have done yesterday before I posted), and it notes that in my climate, the coolant/water ratio should be 35%/65%, not 50-50. In either case, adding the small amount of water that I added yesterday probably has not altered the ratio to any great degree.

BS! Read this: http://www.nichols.nu/tip514.htm

Funny, I found that very same web page and almost posted the link myself. :)

Posted by Go48: "Are you reading this with the engine warm? (Always take the readings with the engine fully warmed up.)"

Hmmm, my owner's manual sez between "L" and "F" with the engine cold. I can't say which page 'cause I ainna gonna go out to the garage tonight as it's damn cold outside.

Yes, distilled as opposed to tap water!

Hence, one of the main reasons for utilizing a recommended solvent/solute mixture. Allow the coolant/anti-freeze to react with the water and it shouldn't bother the plumbing. Using hard water leaves calcium and magnesium deposits in your system, while using soft water leaves sodium deposits. Distilled water in this case seems to be ideal.

Well, I have seen the blood red rust from distilled water so I will humbly disagree, but feel free to use whatever seems appropriate to you.

Absolutely false. Distilled water doesn't "remember" and long for what kind of minerals it "used to have" and even if it did, they were almost certainly of different percentages and composition than the metals in the cooling system. Distilled water mixed in proper proportion with antifreeze, is what you should use.

Yup, I checked the manual and you are correct. My mistake. Most of my previous cars have said check it when warm. Oh well, it's the old RTFM thing I guess. :o

Then you repeated the same experiment with tap water and saw what ..............

I imagine anything you put in will result in blood red rust water if the cooling system is not flushed per manufacturer recommendation or every two years.

Haze,

Your confusing "Demineralized/deionized" water with "Distilled Water." All your arguements hold true for demineralized water, but not for distilled.

Does anyone know if flushing the radiator and replacing with high performance coolant (like amsoil and redline make) really keep the engine cooler than normal antifreeze?

Someone please tell me the difference between deionized water, and distilled water.

As far As I know....they are both water with no disolved ions.....so how are they different...other than the process that they are formed????????????

I believe the thermostats or thermatic bypass valves will begin to allow water circulation only when the water temperature gets to a certain point. The car's ECU is probably programmed to trigger the cooling fans at the radiator throughout a particular temperature range as well.
In other words, the high performance coolant is going to get to a certain temperature whether you like it or not. Using it might help to dissipate heat faster, though.

Actually, I believe that I am completely confused.

I did a little searching around the net and could only find one engineer willing to side with me. Most engineers believe that distilled water is the way to go so I will drop my objection. As for deionized water, I have no idea. I got this opinion from a friend in the 80's who put distilled, definitely distilled water not deionized into his dodge ram 50. About 10,000 miles later the coolant, properly mixed with prestone, his coolant was bright red from rust. Now, to me that seemed like a bad thing, but it is possible that I am ascribing the rust to the wrong source! That truck wasn't exactly new so maybe it was just a bad coincidence. Anyway, you guys swayed me, although I'm still going to use tap water. It's always worked fine for me with no serious deposits, and I have seldom had a car that lasted less than 150,000 miles.

All the best and sorry to have caused a ruckus!

In general a ph of around 10.0-11.0 is the best at inhibiting general corrosion, for most steel alloys. So sure distilled/deionized water can allow corrosion (ph of ~7.0). But tap water is far worse as it is acidic in most areas, and a ph < 7 will accelerate general corrosion. Chloride impurities in tap water can cause severe localized corrosion particularly in areas of low flow.

My friend who uses tap water just blew a head gasket on his Ford Tauris :D.

He said his dipstick showed the oil mix level to be 6 quarts high. He's says he's going to keep using tap water :confused: in the used Pontiac Sunfire he just bought to replace the blow gasket vehicle. ;)

The freezing point and boiling point of a coolant mixture are important. BUT YOU ALL MISSED A IMPORTANT ROTARY POINT: This engine has both aluminun and iron castings. These are dissimular materials and you need the coolant to remain at a high antifreeze concentration to prevent electrolis corrosion. Anyone that has had a number of the older RX7 motors apart should have noticed that some had holes between the water jacket and the exhaust port or spark plug. These were the engines that the owner had not maintained proper coolant mixture. So even in LA a RX8 owner should keep a good mixture of antifreeze.