De-ironized water or tap.

I need to do a coolant change and I'm wondering if it's better to use deironized water mixed 50/50 with antifreeze or use tap water mixed 50/50 with antifreeze , some think it's better to use deironized water ?? Please help.

My car has 86000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
You should not use tap water since it has added chlorine, calcium, and other additives that de-ionized water will not. You can purchase coolant already pre-mixed 50/50 or mix it yourself with de-ionized water and coolant mixed 50/50. You can also use distilled water if you cannot get or find de-ionized water.

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Ideally, this would be distilled water. You can also use bottled water or tap water. Bear in mind that tap water or bore water contains minerals that can leave deposits throughout your cooling system, contributing to corrosion and reducing the lifespan of the radiator.
You shouldn`t really use distilled water as it may oxidize with the metal parts in the radiator. Rather use the OEM coolant mix.
Distilled water has no added minerals (the type you`d find in well water or city tap water), which prevents mineral contamination inside of your cooling system. It`s been steam distilled to remove all mineral impurities, making it safe for use in your BMW`s engine and cooling system.
I have always used tap water, and I make sure to replace coolant every two years. tap water. no problems. but remember to add antifreeze for winter, obviously.
Technically speaking yes you can use plain water in your cooling system but it isn`t recommended as a long term solution and certainly not in extreme weather conditions.
It helps eliminate impurities coming from the tap or bottled waters in the laboratories for chemical reactions in lab experiments. Deionizing removes ions and other unwanted particles, which reduces chemical reactions between dissolved solids. This makes the solution purer, with fewer substances left behind.
They need to be combined to create the good coolant. You can purchase ready-made mixtures of coolant that already have water added, or you can purchase full-strength antifreeze which needs to be diluted with distilled water before being added to the engine system.
You can buy 50/50 premix at any auto parts store that you should be able to mix in with whatever is in your car without issue. The specific heat of water is quite a bit higher than glycol, so pure water will cool better than water diluted with glycol. You don`t want to use tap water, use distilled water.
The BMW radiator antifreeze concentrate is colored blue-green.
Always mix it with distilled water. And the way you do that is before you pour anything back into the cooling system or put it in at any time, you mix coolant and distilled water fifty-fifty, then you put the mix in.
By itself, distilled water, is much better at heat transfer compared to antifreeze/coolants. However, water, by itself, causes the metal parts in the cooling system to corrode. Antifreeze/coolants also cause corrosion, but modern versions of the product have been infused with rust inhibitors.
Yes, as long as you mix it with antifreeze, deionized water is an excellent choice. It won`t leave scale build up in your cooling system. Regular water contains hard water minerals which can leave a build up of hard water deposits in your cooling system.
Always mix it with distilled water. And the way you do that is before you pour anything back into the cooling system or put it in at any time, you mix coolant and distilled water fifty-fifty, then you put the mix in.
Ideally, you should only use de-ionized (DI) water when mixing antifreeze/coolants. However, it can be acceptable to use reverse osmosis (RO) or distilled water depending on the immediacy of the need to mix coolant and availability in your area.

Relevant Questions and Answers :

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De-ironized water or tap.
ANSWER : You should not use tap water since it has added chlorine, calcium, and other additives that de-ionized water will not. You can purchase coolant already pre-mixed 50/50 or mix it yourself with de-ionized water and coolant mixed 50/50. You can also use distilled water if you cannot get or find de-ionized water.

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Can a jeep run and drive without a water pump??
ANSWER : Driving or running the engine without the water pump working to circulate the coolant through the motor will cause the motor to overheat and may damage the engine costing thousands of dollars versus using a tow truck to take the vehicle to the shop that will cost a lot less. I would not recommend running the engine more than a few minutes at a time or you will overheat it.

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Car does not get to normal engine temperature
ANSWER : Hi there:

There could be multiple issues causing your engine to not reach normal operating temperature. However, continuing to add water instead of coolant to your motor could be very harmful; especially to cooling hoses, connections and cooling system components. The coolant should be mixed at a 50% water to coolant ratio. In order to determine why your engine overheated in the first place and why it’s temperature is low now, the best thing to do is have a professional mechanic complete an engine is leaking coolant inspection. This will allow them to inspect your cooling system for issues and recommend the right repairs.

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Is leaking water but the thermostat the water pump and the heater core is good but it’s slowly dripping water onto the ground
ANSWER : Based on your description, you may have a small leak somewhere in the connections to your radiator, water pump or to your engine. Often times water leaks start out small and develop over time increasing and decreasing depending on the temperature of the water. I would recommend having an expert from YourMechanic come to your home to diagnose and repair your cooling system.

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Water was spilled in the trunk which soaked the car battery. Car won’t start now. Does water destroy a car battery?
ANSWER : Hi, thanks for writing in about the concern with the BMW 320i. If the battery was submerged in water then it’s completely possible for the battery to short out and die. Your friend will need to have the battery replaced. Also be sure to get all of the water out of the trunk. Have a certified technician, like one from YourMechanic, help you guys out if you need assistance with replacing the battery. Good luck.

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My water pump is leaking but I replaced timing belt and pump a year ago. Can I just replace the water pump this time?
ANSWER : Hello. You can just replace the water pump in this case. Although, the cost of just the timing belt is fairly negligible in comparison to the total labor of the job. My estimator says the water pump is a 6.5 hour job. Multiply that by whatever the shop rate is and you have the total labor without parts. You end up saving about $100 or less on parts if you only replace the pump.

The deciding factor will be the condition of the timing belt. If it has problems, you won’t be saving yourself any money by reusing it. In addition, there are seals and pulleys that may need to be replaced as well.

Assuming all the related parts were replaced the first time around, there isn’t a reason you can’t reuse them. I would say you should weigh the savings of reusing them against the actual condition of the parts. This is best determined after a complete disassembly. Keep in mind, time estimates will vary a bit depending on many factors. Either way, the labor is the largest cost.

If you would like to have the water pump replaced, a certified professional from YourMechanic can come to your car’s location to perform this service at your convenience.

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It runs hot and theres (NO Water In Oil Pain) but theres water in the valve covers
ANSWER : One possibility is to pressure test the system when cold and look for visual indication of the leak point(s). You might have multiple leak points though and that has to be considered. As far as the overheating, leaks that bleed off pressure can contribute to overheating (much as a faulty radiator pressure cap would) but a head gasket leak into the coolant, thus causing overheating, also has to be checked by testing for exhaust gas in the radiator. After all the leaks are fixed, if overheating continues that has to be further diagnosed. During a mobile visit, YourMechanic can test for leaks and then advise you as to your repair options.

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My car ran hot yesterday and I let if cool and put water in it it cranks but it goes dead if I put water in it it stays on
ANSWER : Hi there. In general, when a car overheats it tends to cause excessive steam or hot coolant to spill in the engine compartment. This can cause electrical components to have problems with connections and have difficulty starting. The solution to these common problems is to first determine what is causing the overheating issue initially. You should have a professional mechanic come to your location to complete a car is is overheating inspection to begin the process of diagnosing these problems.

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