Coolant water choice

Do you guys use distilled water? Filter water? Or just regular city water? I have noticed there is a white dusty residue where the coolant had over flowed out of the reservoir. Have anyone seem the same? TIA

I use filtered water. No sense putting calcified city water in there especially since our area has very hard water. Some guys only use distilled water. What the hell....it's not that expensive if you just have to be sure...... The crusty stuff you're seeing is the residue left over from the coolant Porsche uses. Too much of that white "crusty stuff" is usually an indicator of either a bad coolant cap or a leaking coolant tank. There are a lot of discussion threads here on the subject of coolant tanks....you might want to do a search.

Distilled. I just can't imagine putting minerals in the system, and if you think that filtering takes them out, come on up to my country place and have a look at the kettle, despite a very expensive, four stage water treatment system that includes iron wash, softening and particulate filtration. Distilled, like it says in the manual. Just buy a jug at the drug store. Surely even the most jaded conspiracy theorists around here can't come up with a reason Porsche would misguide us on that?

+1 on distilled.

Distilled.

i just did a coolant flush on my 9 and used distilled to filler er up, well plus the coolant......

My Porsche prefers this because it comes from North Carolina and the bottle is a similar color to the car.

The fewer minerals in the water the better. Here is some guidance on making sure the coolant expansion tank is fully sealed.

I would have said distilled but ive sence read otherwise. Distilled has no ions in it, they are distilled out, so the ions are taken out of the aluminum and thus can corrode the internals. The coolant has some in it to prevent this but its now suggested you use regular bottled water or tap water. And never use any reverse osmosis or anything like that, thats too pure so i have been told. I wish i had a link to validate this but take a look at some contemporary reports on this and you may find similiar findings.

Better tell Porsche. Once again, their manuals are lying to us in an effort to destroy our engines and the reputation of the brand, while creating liability for the corporation. It's a strange business model, but what do I know...

Again, This is something that now goes against my experience. Its somethign I just read about not specific to porsche but was I believe specific to aluminum heads. I am not a chemist, I dont know the real deal with ions and whatever but thats what the article said. So take it with a grain of salt? And does porsche say in their manual to use "distilled water" or does it just say water and Porsche coolant? Does it specify distilled? Ive never read that come to think of it.

It does. By the way, the 'grain of salt' pun was a good one.

In searching the owners manual for the 02 996, in the 2 sections that reference coolant, anti-freeze, and the mix of water to anti-freeze, I did not find any specific recommendation to use distilled water. In a further search of the service manuals for the 996 (group 1, section 19, engine, cooling systems) I still did not find any reference to distilled water. In a broader Google of automotive cooling systems and distilled water, I found many recommendations for distilled water, and a few discouragements, but no concrete evidence of benefit or harm. Personally I have using distilled water mixed with anti-freeze in aluminum engines for over 30 years with no harm done, but there does not seem to be a body of evidence to support or discourage it other than it "seems" logical. Certainly I have not come across anything written by Porsche to require it in their engines. If someone has a definitive reference to the contrary, I would be interested in seeing it.

Distilled water is very corrosive, but the coolant contains a corrosion inhibitor. It would be a really bad idea to use only distilled water, but nobody here is talking about doing that.

Appreciate your homework, but I'm quite certain I was acting on written instructions when I did coolant. I'm like that. If it doesn't say so in the manual, then it almost certainly said so on the jug of Porsche coolant I bought. I'll check when I'm back in the city.

Bruce, I just looked at some Dex-Cool that I just put in my car and read their filling instructions. It states very clearly that you are to fill with "Clean tap water" I had always read or been told to use distilled by someone, or read it on someone's website, but I dont think Porsche does or has ever for that matter specifically stated that you are to use distilled water. It seems I was wrong with what i said previously about distilled water, I guess the article i read previously should have mentioned de-ionized water, not distilled as i had said earlier. Below is a copy of something I found on the web, should answer some questions if you trust the source. "Water Cooling Liquid A final yet important consideration to make is water cooling coolant type. Theoretically, you could fill your water cooling system with anything, but some fluids work much better than others. First of all, do not use tap water. Tap water has minerals, bacteria, and algae in it which will corrode and cloud your water cooling system, possibly causing a catastrophic failure. Another alternative is de-ionized water. De-ionized or non-conductive water may seem desirable initially, because it is a poor electrical conductor, and therefore will not cause much damage if a leak occurs. However, water is an excellent solvent, and so if de-ionized water is put into a water cooling system, it will corrode the water blocks to get its ions back. Therefore, de-ionized water is not something we recommend, either. A good choice is distilled water, because it is relatively cheap yet pure enough to use in a water cooling system. Distilled water will not deposit harmful minerals in your system, nor will it cause algal blooms because there are no living organisms present. It will not, however, corrode your water blocks because it is not de-ionized. There are various additives which may be added to the coolant in your system. Water wetter is great for increasing the cooling capacity of your system by altering the properties of water and making it even more thermally capacitive. Water wetter will also help reduce corrosion in your water cooling system. Other additives, such as UV-reactive dyes, may be added for aesthetic reasons. "

how about redline water wetter

+1 on distilled water mixed with Porsche coolant.

I also find that there are conflicting opinions on its use in automotive cooling systems as well. Take a look at the attached spec sheet for Texaco DEX-COOL, especially their pre-diluted 50/50 product. Read the first paragraph, and tell me what you think. Click here for the DEX-COOL specification.

The wording of the quote betrays the writer as being someone who is conveying information he heard or read somewhere, but does not understand what he is saying. Poor electrical conductor .... damage if a leak occurs" makes no sense. "Water wetter... making the water more thermally capacitive" is incorrect terminology, and if they meant "increases the thermal capcacity of water" that is just incorrect. Additives and antifreezes reduce the heat capacity of water. Water wetter is supposed to reduce the surface tension of water to reduce localized hot spots, but I would guess any good coolant does that anyway, making further additives unnecessary, but good products for snake-oil salesmen. The purest water is is water that has been filtered by reversen osmosis to remove most impurites, then is deionized through ion exchange media. The water then has a resistivity of 18 Mohm-cm. This water is corrosive as it will dissolve engine metal if used alone, but the corrosion inhibitors in the coolant will prevent this, so it is fine to use in your engine. The distilled water (single distilled) from the grocery store is generally not high resistivity because the equipment used to distill it was metal and it dissoved some of that metal already. That water generally OK to use in your engine, although supermarket water can vary over almost two orders of magnitude in resistivity. Why Dex-Cool suggests clean tap water, is a bit of a mystery to me. Really clean tap water is ok, but how do they know how pure your tap water is? Well water or water treated with a water softener is a bad idea because of high levels of dissolved mineral ions and ionic sodium, respectively. If this all worries you, buy a pre-diluted coolant mixture so you don't have to add water at all.

There you go... "DE-IONOZED" water is the key.

well i am going to bow out here. I had read not to use de-ionized, then it shows that 50/50 mix has de-ionized water in it. I will just stick with distilled and be done with it.

Interesting debate. I think I will stick with distilled water for now. Have anyone tried the coolant from VW dealer? I have heard that it is the samething Porsche uses and 1/2 the price. I have noticed the new water pump is leaking coolant again. Coolant is coming out of the shaft area I see evidence of chalky material around the bottom of the water pump. What's the story on water pumps leaking? I have read that several owners have had their water pumps replaced several times already. Is it normal to expect a small leak? The pump pulley is not wiggling and it is not making noise, it will move freely when I turn it, but will not spin freely there is a slight drag from the rubber seal. I can hear the rubber seal squeal when I gave the pulley a turn.