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Freude am Fahren
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Discussion Starter · #1 ·
Found this linked to in archives:

Stu Ritter said:
The latest Mercedes-Benz Specifications for Service Products lists 45 approved coolant products made around the world, from South Africa to Korea, but non are available in the U.S. or Canada! The only approved antifreeze that Americans and Canadians can buy is MBUSA's part number 000 989 08 25. While most U.S. antifreeze meets corrosion protection levels specified by Mercedes-Benz, its pH is unsatisfactory. Fresh domestic antifreeze has a pH in the 9.5 to 10 range, which is extremely basic. According to Mercedes-Benz, the allowable pH range of the coolant mixture is 6.5 to 8.5. MBUSA's antifreeze has a measured pH of 7.5 to 7.8, which, when mixed with water, drops to 7 to 7.5. The buffering (pH maintenance chemistry) of MBUSA antifreeze is excellent, so the coolant mixture remains neutral, neither acidic nor basic, throughout its service life. Domestic coolant mixtures remain very basic, starting with a pH of 10 or higher and slowly absorbing acids, dropping to 8.5 to 9.0 during normal life."
"In our experience, radiators with plastic header tanks last far longer and have far fewer broken upper hose necks if factory antifreeze is used. Look at radiators with broken necks, and you'll clearly see where overly basic coolant has eaten away the plastic, which has become embrittled. Most failed necks that we see are actually crumbly. We have found much longer radiator life in cars using MBUSA coolant exclusively."
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Thus, according to Mercedes-Benz, a huge component of the cooling system failures is the extremely basic (high pH) coolant we are putting in our engines.

What's the Bimmerfest take on this theory? When I do my cooling system is it worth it to buy the MB unobtanium coolant over the BMW unobtanium coolant?
 

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Freude am Fahren
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6,378 Posts
Discussion Starter · #3 ·
Yeah I know :|.

Dirty ex-chrysler-knockoff bits in my BMW?
 

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This has been brought up from time to time and the general thoughts are from what I remember are as follows--best bet for longevity of our cooling systems would be to drain the system at least every 2 years and replaced with fresh BMW coolent.
My cars cooling system lasted a full 100k miles until I overhauled the system a year ago. I'm planning to
flush and refill again in late summer--then I will have a year and a half on the coolent. It takes about a gallon and a half
of coolent mixed with distilled water--so next time I'll just buy 1 gallon instead of two.
Of course though I am trusting that the OEM coolent is of the correct PH level--might have a problem
though because that would mean I would be trusting BMW NA.
 

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Freude am Fahren
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Discussion Starter · #6 ·
Of course though I am trusting that the OEM coolent is of the correct PH level--might have a problem
though because that would mean I would be trusting BMW NA.
That's what I was wondering about primarily. If I had more money I would get some pH paper and run some tests…but I just forked out a murderous $1500 for snows…they better be better than f'n 4wd!
 

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Since its only around 500 dollars to overhaul the cooling system, why would you spend so much money on special coolant that MIGHT make the system last a few thousand miles longer? :confused:
 

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Freude am Fahren
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Discussion Starter · #8 ·
I dunno how much MB charges for the coolant but I can't see it being a tonne more than BMW coolant. The pH scale is exponential; the difference between 7 and 10 is very large.
 

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'03 540, '03 M5
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Sure makes sense.
Thanks for your input, Mark.
I change my fluid regularly, and the car just had the cooling system done prior to my purchase, but I damn well plan to get 200k+ out this car.
If walking aroud the car 3x while the sun rose would make ANY difference, I'm on it!

HB
 
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