Why Zerex G-05 concentrate and prediluted differ?

[porcupine73]

Hello, seeking a suitable aftermarket coolant for my Subaru's. Subuaru says "only a phosphate, non-amine coolant formula is acceptable". Here's the article It appears G-05 might be the closest aftermarket choice? A few questions:

a. Why the difference between Zerex G-05 concentrate and prediluted? Specifically, the concentrate contains sodium tehtraborate pentahydrate (borax), while the prediluted (ready to use RTU) contains sodium benzoate.

Product Name: ZEREX G-05 AFC 6/1 GA (concentrate)
Code:

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Ingredient(s) CAS Number % (by weight)

-------------------------------------------- ------------- -------------

ETHYLENE GLYCOL 107-21-1 89.0

DIETHYLENE GLYCOL 111-46-6 0.0- 10.0

SODIUM TETRABORATE PENTAHYDRATE 1330-43-4 0.0- 7.0

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Product Name: ZEREX G-05 AFC RTU 1/5 GA (ready to use)
Code:

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Ingredient(s) CAS Number % (by weight)

-------------------------------------------- ------------- -------------

ETHYLENE GLYCOL 107-21-1 47.0- 47.0

DIETHYLENE GLYCOL 111-46-6 1.0- 7.0

SODIUM BENZOATE 532-32-1 1.0- 6.0

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b. I am interested in the difference because the Subaru OEM coolant lists the exact same ingredients: ethylene glycol, diethylene glycol, sodium benzoate, but it also has potassium hydroxide (KOH) which Subaru says "its role is to help keep the coolant balanced by controlling pH." Can I maybe add some KOH to the G-05 or just not worry about it? Maybe I should use the prediluted because it has the sodium benzoate which more closely matches the OEM coolant?

It's interesting to note that in the article, Subaru says "we've never seen a similar list of
ingredients listed on the container of any other brand of antifreeze." Well that's funny since the Zerex G-05 prediluted says the exact same thing minus the KOH.

 

[Eddie]

I use the G05 in my 2000 Forester for the last 104,000 miles without an issue. I do change it at ~ 35,000 miles. Pepboys for ~ $9.00 per gallon and mix with Walmart distilled water for a 50/50 mix. Ed

 

[y_p_w]

Thanks for the Endwrench article. I've been looking for something that confirms that Subaru OEM coolant was phosphated. Phosphates are known to protect aluminum water pumps. I'm still looking for any confirmation that it does or doesn't contain silicates. I bought a bottle for about $14 in Dec 2005 when I happened to notice a Subaru dealer in Carson City, NV and used it for my first change at about 32K miles. It was a little bit over 30K miles, but the article implies that it does have a bit of a reserve to handle going over their conservative recommendations. I actually found a Subaru dealer in Angels Camp (Calaveras County), CA and stopped there to see if they had it. They had it, looked up their price and then told me I probably wouldn't want it - I think it listed for over $25.

The thing that really gets me about coolant labelling is that they're not required to state what their actual corrosion inhibitors are. Prestone does state the use of two OAT corrosion inhibitors on their packaging, but they've often never labelled that it contained silicates or phosphates.

The Zerex G-05 supposedly doesn't contain phosphate. Neither do any of the current major Prestone offerings (All-Makes/All-Models and Dex-Cool). Something about Europeans shying away from phosphate because it precipitates with the typical hard water (from well water) there. It doesn't sound good if your coolant suddenly forms abrasive particles and the corrosion inhibitor that's supposed to be there just lost a good chunk of its protection. Of course it's not a problem if the water is relatively free from minerals (I use distilled water).

Potassium hydroxide isn't that unusual. It's used in all sorts of things. Sodium hydroxide (lye) is used in some aquarium pH balancing kits, although I preferred to use something a little less toxic straight up for my fish tanks.

I wouldn't take it that just because you see certain ingredients on the label that it's similar enough. Like I said - there are plenty of things in there that might not be listed but we know are in there. Prestone, Peak, etc used to call this "proprietary corrosion inhibitors". They might not have been patented molecules, but their blend and/or combinations might have been a trade secret.

 

[porcupine73]

Thanks Eddie for the confirmation of extended G-05 use in your Forester. Say when you replace your timing belt at 105k miles, are you going to replace the water pump too? If so, some pics of the old water pump's impeller and case would lend insight into how well G-05 works with distilled water in Subaru's.

Good points y p w. It is interesting to note that although that article says Subaru wants a phosphate antifreeze, the OEM coolant doesn't actually contain phosphate I don't think. It's the sodium benzoate they say performs that function. They say "...phosphate is nowhere to be found on the label...Sodium benzoate and phosphoric acid (a derivative of phosphate) are virtually interchangeable. They do the same thing, but come to it via a different
chemical makeup."

I bought some more G-05 concentrate today since napa didn't have the prediluted in stock. I think the MSDS's I got the info from leave something to be desired. The G-05 concentrate lists both the borax and sodium benzoate as ingredients, along with corrosion inhibiters, defoamers and dyes.

 

[g20ooh]

I'm just going to guess here that it somehow slows the additive degradation that occurs with any concentrate formula once you get above a " true " 5-12% water concentration ie mixed .
Every additive pack is water activated although some in the past at least had different water levels and activation properties . This is not the only premix that gets tweeked when sold 50/50 .
Borate anything tends to be shorter lived in service - more a time in solution then thermocycles etc kind of thing .

 

[JohnBrowning]

Probably due to the water content and it's PH. Even though G-05 is designed for Germany's hard water I would use distilled and reap the added benifitts!

 

[y_p_w]

Quote:

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Good points y p w. It is interesting to note that although that article says Subaru wants a phosphate antifreeze, the OEM coolant doesn't actually contain phosphate I don't think. It's the sodium benzoate they say performs that function. They say "...phosphate is nowhere to be found on the label...Sodium benzoate and phosphoric acid (a derivative of phosphate) are virtually interchangeable. They do the same thing, but come to it via a different
chemical makeup."

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I don't know if labeling is really that great an indicator of the exact composition. I've been using phosphated Honda coolants for years, and the label never said much beyond just ethylene glycol and diethylene glycol. Legally I don't think they have to state anything beyond the toxic materials that would be listed in the MSDS.

I do have a whitish condensation on the overflow tank tubes. When I spilled a bit of factory coolant on the high tank of my WRX, this also had a whitish residue when it evaporated. It's probably a mix of the corrosion inhibitors, but I was thinking it might be mostly phosphate or silicate (still don't know if there's silicate in there.

 

[g20ooh]

I'm with you there John as long as the OEM doesn't expressily prohibit - and only if I was using that particular coolant . I run distilled in everything but admittedly my mixes and applications are slightly different than most .
One thing I came across last night from what appears to be a creditable source was the observation that Asian HQed OEMS thru 1st quarter 2005-2006? do not use any type of borate even in HD DIESEL apps - actually feel as strongly about that as they do silica etc .This maybe out of date on newer production . Also that they feel a phosphate helps deal with glycol breakdown product better and provides a more efficient skin in terms of heat transfer although not as good as a pure OAT .None of this was quantified BTW . They don't appear to be big on nitrites either although that varies / seems to be changing ? to some extent .I've broken every rule possible on certain old Infintis and a few others as well but I think I'd be more careful on a Subie and just about anything past 2000/2002 .
We really are more in the dark W/O good information than many realize .
Its not so much about corrosion protection - everything in production today is at least decent when used as intended -as it is about seal and gasket compatibility and sometimes thermal transfer charactoristics .I think alot of it has to do with who as an OEM buys what from whoever .One thing no one ever mentions in regard to the European makes is the high phosphorous content of their automotive iron and steel .

 

[g20ooh]

I don't think I have ever seen a complete additive list with less than 10-12 compounds and some of the all metal types are considerably more than that . Of course , its a package but there are plenty of ratios that vary within a package and then there is the fact many standards are not ingredient specific but are performance driven .......
and then formula development overtime .....of which there has been a great deal of since 1998 ......I don't think alot of coolant is exactly what we think it is which is really bothersome when trying to determine what your good/best choices really are outside of your OEM supply - esp when cost is considered .