cooling system
Super Member
Joined: Aug 2005
Posts: 591
Likes: 9
From: Covington, WA
'96 SL600, '05 S55 AMG, '06 C230
Off-the-shelf distilled water should not be a problem for cooling systems. Although I'm not sure what the advantage of it would be over tap water. Unless you have an all-stainless steel cooling system, once the water is installed, it picks up all sorts of stuff from the engine block, radiator, etc. Sort of defeats the purpose, I think.
However, what FJ may be referring to is to not use deionized water. This is sometimes confused with distilled water - but they are two separate purities of water. Tap water has a relatively low electrical resistivity (mainly from contaminants). Distilled water is purer water - essentially bottled water, that creates a relatively higher electrical resistance. Deionized water has an extremely high electrical resistance, but it can also cause etching & leeching of metallic surfaces through aggressive electrolysis.
In general, it is tough to find true-definition deionized water readily available. Nevertheless, some folks still get distilled water and deionized water confused.
However, what FJ may be referring to is to not use deionized water. This is sometimes confused with distilled water - but they are two separate purities of water. Tap water has a relatively low electrical resistivity (mainly from contaminants). Distilled water is purer water - essentially bottled water, that creates a relatively higher electrical resistance. Deionized water has an extremely high electrical resistance, but it can also cause etching & leeching of metallic surfaces through aggressive electrolysis.
In general, it is tough to find true-definition deionized water readily available. Nevertheless, some folks still get distilled water and deionized water confused.
Last edited by MB-Dude; Aug 3, 2007 at 12:22 AM.
Thread Starter
Member
Joined: Jun 2003
Posts: 219
Likes: 1
From: Irvine, CA
2000 CLK430
yeah, this is really confusing...when i read the owners manual it mentioned only using drinking water for the mixture. nothing about distilled water.
on the other hand, i have a honda also and the manual specifically mentions using distilled water.
trust me i would rather use distilled water, but if for some reason, benz blocks don't like distilled, then i won't use it.
the service manager specifically said that, i should never use distilled water for the mixture.
on the other hand, i have a honda also and the manual specifically mentions using distilled water.
trust me i would rather use distilled water, but if for some reason, benz blocks don't like distilled, then i won't use it.
the service manager specifically said that, i should never use distilled water for the mixture.
Super Member
Joined: Aug 2005
Posts: 591
Likes: 9
From: Covington, WA
'96 SL600, '05 S55 AMG, '06 C230
Man, if there is something in writing from MB that specifically says 'do not use distilled water', I'd love to see it along with an explanation of why. There is little difference between tap water and distilled water, except for the purity. And how can something more-pure be a bad thing?
By the way, drinking water can be either clean tap water or distilled (off-the-shelf) water. I suspect MB specifies 'drinking water' in their manual as there are parts of the world where tap water is not very clean. Water coming up from underground wells, for example, can be considered 'tap water', but not fit for drinking until purified through filtration; too many suspended solids in the liquid.
By the way, drinking water can be either clean tap water or distilled (off-the-shelf) water. I suspect MB specifies 'drinking water' in their manual as there are parts of the world where tap water is not very clean. Water coming up from underground wells, for example, can be considered 'tap water', but not fit for drinking until purified through filtration; too many suspended solids in the liquid.
Last edited by MB-Dude; Aug 3, 2007 at 08:46 AM.
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Joined: Jul 2004
Posts: 31
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From: GTA Ontario
02/ C230 Coupe
Distilled Water
I for one use nothing but distilled water because it contains no clorine or minerals that would attack the metal interior of the cooling system. I have seen deionized water on the shelf that says for cooling systems but still prefer distilled right out of my dehumidifier. I also use Redline Water wetter with MB coolant. 
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Joined: Apr 2005
Posts: 3,784
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From: SCV SoCal
2002 CLK430
We must on the same cooling system schedule as I did mine in the CLK last week.
Distilled water and Zerex G-05. Valvoline (the parent company of Zerex) says to use distilled water.
Distilled water and Zerex G-05. Valvoline (the parent company of Zerex) says to use distilled water.
