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Old 07-29-2002, 02:13 PM
csnow's Avatar
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Join Date: May 2002
Location: Mass
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There is another school of thought regarding the use of distilled water in cooling systems.
Distilled water has no minerals, which on the surface sounds good. Who wants minerals in their cooling system, right?

The supposed problem is that distilled water is therefore 'hungry' for minerals, and it will need to get them from somewhere until it reaches a saturation point where no more minerals can be dissolved into suspension. These minerals will come from the metal components in your cooling system, such as your engine and radiator. Significant? Worse than calcium? Perhaps not...

I am curious if anyone has more data on this theory.
1986 300E 5-Speed 240k mi.
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Old 07-29-2002, 04:30 PM
ML Dude's Avatar
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Location: Southern California
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Whether distilled water is more reactive near it's boiling point than tap water is a question for chemists. But, my old english mechanic mentor once told me not to use distilled water in the radiator.
I never have nor have I ever had to replace any cooling system components in any car except my 300E. It was leaking a little around the water pump and then broke it's neck at the top of the radiator, both well known problems with this model.

This level of care is interesting since my new V8's seem to run hotter than other engines I've owned. I'll watch to see what the majority opinion is on "water" Sparkletts or Arrowhead
Ed "Don't Benz's just feel better..."

Current wives...
2000 ML430 Skyview "The Mel"
2000 CLK430 Cab "The Cab"
85 300D Turbo "The Diesel"

Past wives...
92 300E
85 190E

"One should as a rule respect public opinion in so far as is necessary to
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this is voluntary submission to an unnecessary tyranny, and is likely to
interfere with happiness in all kinds of ways."
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Old 07-29-2002, 04:36 PM
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I've never seen any Redline Info which recommended insane water to coolant ratios. A ratio of 70% coolant is going to result in overheating. The only thing I've seen them mention is 50/50 ratios in passenger vehicles or pure water in racing engines.

For anyone who wants proof and doesn't buy the proof on Redline's site at then I suggest forgetting about it.

Yes, you cannot use distilled water by itself but when it's added to an anti-freeze, the problem goes away.

All of this has been discussed by the now deceased Frank King who was the Technical Editor for the Star Magazine for decades.

Redline is a very reputable company. We're not talking snake oil products like Slick 50. Redline probably make the best oil for passenger cars that's available in the US. Redline and Mobil 1 oils are probably used in the majority of racing engines competing in the US, even in those race cars that are sponsered by another oil company.
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Old 07-29-2002, 04:40 PM
I told you so!
Join Date: Jun 2002
Location: Motor City, MI
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In my post I didn't cite opinion about calcium being poison, rather this is published data from "Automotive Engineering", a respected journal among automotive engineers.
95 E320 Cabriolet, 131K
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Old 07-29-2002, 05:03 PM
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Location: Fairfax County, Virginia
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The ratio I noted was 70% water and 30% coolant ... this gives better than 50/50 cooling, right?

I was told that WW specified this 70% water/30% coolant ... the net effect of which is to increase the cooling capability, right?

So, the question is, then: if I use 70% water, 30% coolant without WW, will it run cooler or act any differently than if I add WW?

BTW, I trust few websites ... particularly if they are selling something ...

Does Redline have any competition in WW type products? If now, this is really getting weird.

Maybe 60 Minutes should work on this one!
George Stephenson
1991 350 SDL (200K and she ain't bent, yet)
former 2002 E320 4Matic Wagon - good car
former 1985 300 CD - great car
former 1981 300 TD - good car
former 1972 280 SEL - not so good car
a couple of those diesel Rabbits ...40-45 mpg
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Old 07-29-2002, 05:26 PM
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Did you check out the link I posted. It takes you directly to the technical data on WW including test comparisons.

Redline happened to discover WW while they were trying to come up with a solution to another problem. I doubt they have any competition so maybe it's still protected by a patent.

Yes, 70% water will run cooler than 50/50 but then you must add Water Wetter or another source of additives to provide adequate water pump lube, etc.

I buy MB coolant and pre-mix 50% distilled water, 50% MB coolant and 4 oz. of Water Watter per gallon of the pre-mix. I then drain as much of the old coolant from the engine as I can get w/o opening the block.

I then add back in the pre-mix until it's topped up. I realize that people will say I don't get all the coolant out using this method but I do this yearly so it's constantly being refreshed and there is no tap water in the system.

This costs me about $10/year/car depending on what the coolant costs me. It takes only a few minutes to do it. This method has worked beautifully on my wifes 18 year old 190D and my 11 year old 300E.
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Old 07-29-2002, 05:49 PM
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ive changed today my coolant from the old "GREEN" to the newer pink, just flushed the system.
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Old 07-30-2002, 12:29 AM
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Location: Dubai, United Arab Emirates
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The OEM coolant I buy here in the UAE is part number A 000 989 08 25 to spec. 325.2 and is BLUE. Both my cars run on a 55%/45% mix and I suffer no overheating problems or corrosion on either of them. We cannot get Water Wetter here and I am not sure I would really like to try it as the car temperatures are O.K. for me, although the 500E gets a little warm after some ' spirited ' driving. My personal choice is to change the collant every year and I pre-mix about 5 gallons of coolant and have it in the container as a top off for the rest of the time. I think it is vital to stay on top of the cooling system components all the time as these engines like to run hot all the time.
1993 190E 2.0L (Euro.) sold
1991. 500 SEL (Euro.)
1991. 300 CE (Euro.) sold
1993. 500 E (U.S. spec.)
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Old 07-30-2002, 01:07 AM
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Location: Surrey, Beautiful British Columbia, Canada
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wow, with these colours i'd say, "excuse me
while i kiss the sky."
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Old 08-02-2002, 08:13 PM
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Location: SF Bay Area, CA
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>I've always used distilled water with the coolant.

Wise practice. There's enough precipitatable carbonates in drinking water in most places to really clog up fine passages.

>My question is that is the MB coolant the sam as the newer coolant called Dexcool (which is orange) that is used in the newer GM cars? I have been told that in older cars which have used the old green stuff should not use the mewer Dexcool type coolant because it can actually create sludge in the system.

Let's see if I can remember this correctly:

Both Dex-Cool and MB coolant use organic acid technology for anticorrosion. MB uses a slightly different spin on OAT called Glysantin. Dex-cool is totally nonsilicated. MB coolant has a slight silication. Classic green Prestone is heavily silicated, which is why it tends to eat water pumps.

And yes, dropping Dex straight into a system can really mess it up, especially if there is residual green silicated coolant around. The OAT will react with leftovers and turn into ugly brown sludge.

MB was twice the price of Dex last I looked. But how often does one change coolant, anyway? Even once a year, that's not a huge price hit.

That said, I have an MB V8 here which is happy after a Dex conversion (it was overheating on the Prestone that was in it when we received the car at second hand; it is now cured on Dex.)

What I was told was absolutely critical was to completely flush any remnants of the original coolant, including the often forgotten heater core contents. I did three successive distilled water flushes with a hearty hot drive in between each, and with the heater on full blast to circulate it out. By the third, the flush water was crystal-clear, no hint of any green.

I then installed 50/50 Dex/distilled. No Water Wetter used, as I was experimenting with how well Dex alone would function. Happy car. I have noted no signs of cooling system deterioration or problems at all in a year of service.

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Old 08-02-2002, 10:31 PM
I told you so!
Join Date: Jun 2002
Location: Motor City, MI
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I don't think MB coolant is the same as Dexcool. My owners manual states the coolant in my car requires ethylene glycol. Did they change this in later years?
95 E320 Cabriolet, 131K
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Old 08-03-2002, 12:33 AM
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Join Date: Mar 2001
Posts: 326
I use the clear/yellow MB coolant w/ tap water. Never have an overheating problem.
I service the cooling systems at thier recommended intervals.
What is this "orange" MB coolant I'm seeing mentioned here?
Scott Diener
89 300E
93 300E
92 Volvo 740 Wagon aka "Mutt mover"
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Old 08-03-2002, 09:03 AM
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Scott, I think that the MB coolant when undiluted looks slightly orange, more towards yellow to me too, but if you look right in a new gallon container of it, I can see a slight orange tone to it. Mix it 50:50 and it looks yellow then.
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Old 08-06-2002, 08:24 PM
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I've used Prestone green coolant in my 300E and it works really good but a mix of green and yellow/red will induce immediate rusting of engine. Look at the Motorweek website. If they billed you for MB antifreeze then go back and demand a citric acid wash + a complete flush. If it is just pure green, don't worry that much but a mix will ruin the engine. Prestone is safe for all engines. Perhaps MB has released a secret silent bulletin on 300E and green coolant.

Distilled water is very important. Their might be small particulates in your tap water that could destroy your engine. Remember there is no coolant filter or passthrough. pH should be 7.00. If not distilled must be potable water. Air bubbles should be burped out. Ratio should be minumum to protect against freezing. In So. Cal in my 300E I run 25%. Forget about water wetter, I remember a guy on this board who ran Redline and he ended up switching out his headgaskets.
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Old 08-06-2002, 10:57 PM
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Join Date: May 2001
Location: Portland, OR
Posts: 29
My invoice shows a charge of $20 for 2 gallons of (green)coolant. The last time I bought MB coolant it was $12 per gallon. It sure looks to me the dealer is trying shave costs on "older" MBs.

I will contact the dealer to resolve this in the next few days. Any advise on what the best approach is when going back to a dealer to fix this sort of thing? A complete flush, citric treatment and refill with correct coolant sounds very reasonable to me. Advice?

Thanks again,

'86 300E
256K miles
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