Dex-Cool ... "A Mechanic's Best Friend" ???

[Russ T.]

Purchased a DeWitt's radiator 5 years ago and the manufacturer
recommended that I use Dex-Cool in it. Flushed my system
and filled it with Dex-Cool.

The other day I installed a new engine harness in my '64
convertible and took it out for a drive. Upon returning, I
found that my radiator was blowing like "Ol' Faithful".

Investigated and noticed that radiator was leaking badly in 3 corners.
My records show that I have logged only 4,057 miles
using this radiator. Needless to say, I am disappointed.

This weekend I read John Hinckley's excellent article in the
Restorer in which he states that the Dex-Cool formulation
has issues with leaching the lead out of soldered joints.
At this time my heater core seems OK.

I also noticed that Dex-Cool has a disclaimer that states that
it's long life feature only applies to brand new cooling systems.

I searched the internet and found all kinds of people
raising cane about Dex-Cool eating away intake gaskets,
head gaskets, etc. and generally being a disaster for their
GM cars. There was even a class action lawsuit filed a few
years back.

My radiator guy epoxied the corners of the radiator,
but now I'm reluctant to press my luck with this stuff.
I'll probably go back to the old faithful Prestone.
Has anybody had a similar experience?

Thanks,
Russ Trotter
NCRS #15044

[Michael J.]

Re: Dex-Cool ... "A Mechanic's Best Friend" ???

I have always used Zerex G-05 and have never had any issues with old brass original radiators or new DeWitts.

[Joe L.]

Re: Dex-Cool ... "A Mechanic's Best Friend" ???

Purchased a DeWitt's radiator 5 years ago and the manufacturer
recommended that I use Dex-Cool in it. Flushed my system
and filled it with Dex-Cool.

The other day I installed a new engine harness in my '64
convertible and took it out for a drive. Upon returning, I
found that my radiator was blowing like "Ol' Faithful".

Investigated and noticed that radiator was leaking badly in 3 corners.
My records show that I have logged only 4,057 miles
using this radiator. Needless to say, I am disappointed.

This weekend I read John Hinckley's excellent article in the
Restorer in which he states that the Dex-Cool formulation
has issues with leaching the lead out of soldered joints.
At this time my heater core seems OK.

I also noticed that Dex-Cool has a disclaimer that states that
it's long life feature only applies to brand new cooling systems.

I searched the internet and found all kinds of people
raising cane about Dex-Cool eating away intake gaskets,
head gaskets, etc. and generally being a disaster for their
GM cars. There was even a class action lawsuit filed a few
years back.

My radiator guy epoxied the corners of the radiator,
but now I'm reluctant to press my luck with this stuff.
I'll probably go back to the old faithful Prestone.
Has anybody had a similar experience?

Thanks,
Russ Trotter
NCRS #15044

Russ-----


Yes, there have been a lot of complaints about Dex-Cool since it was introduced but I've never experienced a bit of trouble with it. Dex Cool works very well for cars with aluminum radiators AND heater cores. However, I would NEVER use it in a car that had either a copper/brass radiator OR copper/brass heater core.

I really doubt that the Dex-Cool had anything to do with your radiator failure. However, it will have something to do with your heater core failure when that occurs. Dex-Cool is very easy on aluminum but very hard on solder in copper/brass radiators or heater cores.

Although I used it for many years, knowing what I know now, I would not use the Prestone "green". You can use Zerex G-05, though. For your system, it is the best choice.

[Edward J.]

Re: Dex-Cool ... "A Mechanic's Best Friend" ???

Russ, I have seen many problems with Gm Dex-cool over the years. and it seems that it does not like Cast iron. As with most of the GM cars and trucks I have seen it causes really bad rust once the chemicals break down, and the 5yr 100k change does not seem to last as they say with all engines. Now with the later GM all aluminum engines and radiators it seems to be Okay. Dex-cool seems to likes higher temps. if you have a car with a stuck open Themostat , Dex-cool seems to cause a slimmy sludge in the coolant recovery tanks and radiator. Once the Dex-cool gets to old, Electrolysis will set in and this will eat your radiator, gaskets, seals from the inside out. and you won't know it until its to late.

[Duke W.]

Re: Dex-Cool ... "A Mechanic's Best Friend" ???

I doubt if Dexcool had anything to do with the demise of your DeWitts radiator.

One thing you should do ASAP is to use an ohmmeter to determine if your radiator is electically isolated from the chassis. That's why it's mounted in rubber grommets, and you should also check those. New radiators regardless of type should always get new mounting grommets - two on the bottom and one on the top.

St. Louis did not install the top rubber grommet on my SWC. I always wondered why the top of the radiator had a little fore and aft play, and because of the missing mounting grommet it was electrically connected to the chassis, so the "circuit" between anode and cathode - aluminum and iron was completed allowing for significant galvanic action, and my radiator was seeping in about 12 years. It was the AIM I bought in the mid-seventies that illuminated me on the missing upper grommet.

There are an amazing number of C2s that still have their original radiators, which is probably due to good electical isolation, which prevents galvanic corrosion. But most will eventually succumb to "arterial sclerosis". The tubes clog up with precipitates, particularly silicates and phosphates, from the old "green" antifreeze and lose so much heat transfer efficiency that the engines consistently run hot or overheat.

Use Zerex G-05 mixed 50-50 with distilled water. The green stuff is obsolete. G-05 is the new "universal" antifreeze that is compatible with all metals in vintage and modern cooling systems, including traditional high-lead solders that all C1-C3 Corvettes have at least in the heater core.

Duke

[Paul H.]

Re: Dex-Cool ... "A Mechanic's Best Friend" ???

I have never heard Tom recommend Dex-Cool for any of his restoration radiators.