G12 german coolant

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I've had the original G12 "lifetime" coolant in my Porsche for 5 years. It's described as Nitrite, amine, phosphate, silicate, borate free (OAT). It holds over 7.5 gallons of coolant. The cheapest I can get G12 off ebay for $35/gallon, so a drain/refill will cost $135. If I ever have to drain it for repairs I'd rather not have to pay $100 to refill it. I'd like to convert it to Dexcool or G05 I think. If I convert to Dexcool or G05 do I need to totally flush the system? This car has a long complicated cooling system with 3 front radiators. My tap water is from a well with lots of calcium.
What about running a coolant analysis and only replacing it if indicated by the analysis?
 
G12= DexCool

Fill'er up with Prestone DexCool or their Extended-Life, "All Makes and Models" product.
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If I switch to Dexcool do I need to do a thorough flush? What about with G05?
Does a coolant analysis give enough info to determine if the coolant is still good. Since it holds so much coolant the coolant additives may still be fine(?)
 
They'll mix fine.

Coolant analysis may or may not show that the coolant is suitable for continued use, I don't know.

To make life easier, for the cost of a coolant analysis, pick-up two gallons of Prestone DexCool concentrate and two gallons of Distilled Water. Mix them together in a five gallon bucket. Then drain both your radiator and your engine block and refill with as much 50/50 DexCool/Distilled Water mix as possible. This will surely replace most of the old coolant and refresh the corrosion inhibitors.

DexCool will mix just fine with G-12. If you go the G-05 route, then you'll have to do a full flush, JMO.
 
BASF makes G-12 and the other near-clones for many European automobile manufacturers, and sell three aftermarket coolants under their Glysantin name:

http://www.performancechemicals.bas..._markets/automotive_fluids/glysantin/products

G-05 is used by Mercedes, Chrysler, Ford, and others. It is a bit more tolerant to low-coolant levels than G-12.

It contains nitrite and a low dose of silicate, and is classed as a HOAT.

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=37;t=000161#000000

You could retrofit your Porsche with it, but it would require a complete flush.
 
Zerex recommends their ExtremeLife DexCool product for all G-12 applications.

Also, nearly all coolants on the market today can be safely mixed. However, if you top-off an ext. life coolant with a "traditional" coolant, you limit the working life of the ext. life coolant to that of the fluid you topped off with. G-05 and DexCool can be used to top-off each other, but as with most coolants, they'll probably work best "alone."
 
Hi there,

I used Dexcool Prestone in my VW 86. It stopped leak in the water pump and worked well for 10 years. I did not flush but just kept on draining and refilling and replaced all the hoses.

Spend you money on replacing hoses not on expensive G12.

W115nut
 
I buy my G-12+, the newest version of G-12, from my local Volkswagen dealership. It's $17.80 per gallon and 10% discount is usually available just for the asking.

if you're buying 4 gallons of the stuff I can almost guarantee they'll drop the price a bit.

I personally don't agree that DexCool is the Glysantin equivalent. Zerex (Ashland) does make the BMW, Mercedes, and VW/Audi coolants for North America and they are all proprietary formulations that are not legally reproduced except under patent agreement from BASF.

If your car came with G-12 then I'd specify G-12. If it came with DexCool then I'd specify DexCool.
 
G12+ at $10 per 1.5L doesn't sound like a good price when compared with $17.80 per gallon.

What is meant by "concentrate"?... versus what?
 
I've never seen premixed OEM VW coolant. The concentrate is always to be diluted with 40-60% water, depending on ambient temperature.

The dealer wanted almost 30 bucks for 1.5 liters, but I found it a local parts store for around $10. I'd consider under $20 for a gallon concentrate a very good deal.

 -


[ June 29, 2006, 05:22 PM: Message edited by: moribundman ]
 
quote:

FowVay:
....
I personally don't agree that DexCool is the Glysantin equivalent.
....


The specs are on-line at BASF's German website.

The chemistry of the DexCool type coolants for the various European manufacturers are the same.

There are very slight differences in Ph and so on.

Once you take into account differences in mixing and so on for the aftermarket, you couldn't fit a piece of paper between them.
 
HI Mickey,

For me 86 VW, I started using Dexcool as soon as it came out. I did freak out the VW specialist shops but they see the seepage from the waterpump with dried residue and I had very little if at all drop in radiator level.

My car had green stuff before I started Dexcool. I was changing the hoses (there are nine in that car) and everytime I changed a hose, I would drain and fill with 50% mixture about every three years.

VW runs hot especially when idling in traffic with AC on in 100F. Dexcool worked well in my car, and I had no cooling system problem with a water pump which lasted more than 10 years under heavy use at times and high RPMS. I took the car to Death Valley, kept up with Mercedes SL55 on the way back on I5 at 100mph at 90F weather with AC and loaded car.

W115nut

quote:

Originally posted by Mickey_M:

quote:

FowVay:
....
I personally don't agree that DexCool is the Glysantin equivalent.
....


The specs are on-line at BASF's German website.

The chemistry of the DexCool type coolants for the various European manufacturers are the same.

There are very slight differences in Ph and so on.

Once you take into account differences in mixing and so on for the aftermarket, you couldn't fit a piece of paper between them.


 
It is true that the analysis specifications look very similar between DexCool and G-12. But when you study the ASTM Corrosion Test results you see the results of the differing chemistries.

In my personal experience I have seen deteriorated gasket material when DexCool was used where it wasn't specified. However, by looking at the ASTM tests, the DexCool actually appears to perform better than the G-12. But in product specific applications the results differ.

Examples: (weight loss of parent material in mg's)
G-12 listed first, DexCool second-Glassware corrosion test ASTM D-1384
Copper: 3.2mg vs 2 mg
Solder: 1.4 mg vs 6
Brass: 1.9 mg vs 3
Steel: 2.8 mg vs 0
Cast Iron: 1.6 mg vs 0
Aluminum: 6.4 mg vs 0

Simulated Service test - ASTM D2570
Copper: 16.4 mg vs 2mg
Solder: 2.8 mg vs 5
Brass: 4.9 mg vs 1
Steel: 2.6 mg vs 1
Cast Iron: -4.7mg vs 0
Aluminum: 7.7 mg vs 0

Here's where my concern comes from:

Ford Pitting Test:
the G-12 shows a increase in material of 23.3 mg/sq. cm whereas the DexCool has a loss of material of 120.7 mg/sq. cm.

Due to the different materials used in different engine designs, I still stand by my previous statement that I'd use DexCool only where specified by the OEM. To me, saving a few dollars every 4 or 5 years simply isn't worth the possibility of cooling system deterioration - especially in a engine as expensive as the original posters water cooled Porsche.
 
quote:

FowVay:

In my personal experience I have seen deteriorated gasket material when DexCool was used where it wasn't specified.


The inhibitors, acids, and so on are the same in DexCool and G-12. It's the ratios of them that differ.
 
Mickey, will you please publish the trade names of these items that you mention. Naturally their content percentages will be proprietary but I'd be interested what exact chemicals are used in DexCool.

Thanks.
 
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