Hey, guys.

I recently did a small job where I was required to drain the coolant and refill it afterwards. While I was at Autozone to buy the green Prestone 50/50, the manager, who seems very knowledgeable, explained to me that a risk in using green antifreeze for an engine that's designed to use Dexcool (typically those that have iron heads attached to aluminum blocks or vise versa) is that the green antifreeze can potentially act as an electrolyte with the iron and leech out the aluminum, causing pits and cracks. Is there any truth to this?

The reason why I switched from Dexcool was that I heard it tends to dissolve plastics and rubber. Any truth to this also?

By the way, with the LS1, is there any risk of heat-induced engine damage if you drain the coolant shortly after driving at full operating temp (205°F)?

Thanks for the help.

 

I switched to green **** and got an earful from my brother . Just make sure you got all the dex out if you dont want to run it .

 

https://www.getahelmet.com/jeeps/maint/dexcool/

 

yes there is "some" truth to it, but you can find truth to anything from various perspectives. the way "you" worded it is out of context, and problem is people don't think.
the old green type antifreeze when it hasn't exceeded its service life, works fine. doesn't matter if an engine has previously used dexcool or any other antifreeze or if there's iron, steel, aluminum, or copper.
what happens and this applies to any antifreeze is over time it breaks down like any fluid and then can become conductive... an electrolyte... then any dissimilar metals in contact with it can then have an electrolytic or galvanic reaction and begin to disintegrate. and this was more prevalent on older vehicles using the green antifreeze which was not uncommon to also have electrical problems & bad grounds from rust (people only know how to put gas in tank & go, never check oil, tire pressure, etc.) which then also caused electrical current to flow into & thru the cooling system exacerbating the issue. And I want to say heater cores failing and leaking on the 1980's to mid 1990's cars which i can remember a lot of...were aluminum where the motor was iron ==> see galvanic chart. this was on stuff when i was a kid and no one ever touched a cooling system other than to add water.

yes... but that was only for a certain type of plastic i'd have to look it up. it was used on specific intake gaskets on a certain gm engine which had the problems and gave dexcool the bad rap. once they corrected that, there is no problem with dexcool, and that was the only problem. the LS1 is a dry intake, and there never was any gasket material that i'm aware of on the LS series of engine that EVER had the problem with dexcool, it was one specific model of motor.

[quote]
By the way, with the LS1, is there any risk of heat-induced engine damage if you drain the coolant shortly after driving at full operating temp (205°F)?
[quote]

no, if the engine is off then there is no longer a source of heat to "induce" damage. if you go draining the coolant right after shutting the engine off, you'd be removing heat from the motor... and probably burn your face off.

yw

 

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pages 2,3,4,5

 

it was the 2-eha chemical that reacted with the nylon-66 type of plastic in the intake manifold gaskets used in GM v-6 engines in the late 90's, when dexcool was introduced. if you google that you can still read all kinds of crap about it.

you can also google "ford dexcool mustang"

 

Thank you all very much for your valuable input. I learned a great deal.

When I had first gotten my car, it had Dexcool and the odometer was at 130k. The car would mildly overheat, but the fan was able to keep the temperature close to around the middle (210°F). Eventually, in warm weather it crept up close to the third quarter mark on one occasion, so I had gotten a flush done. That was when the shop had put in the green stuff without my knowledge. The flush didn't get all the Dexcool out and the green antifreeze that was put in afterwards mixed to produce a thick, coffee-like fluid. Subsequent drains and refills for other jobs eventually cleared that up. Later, I became wary of its alleged plasticizing effects, but knowing the facts now, I wouldn't mind using Dexcool again as long as I feel secure that I don't have any leak spots where air could get in because of the way it thickens as shown in the video I found below:


Here's another interesting video that evidently tells of a class-action lawsuit against GM:


I don't know what problems they encountered, but, again, my car had this stuff in the radiator for over 100k.

Something that I neglected to bring up is that, ever since I've had the green antifreeze in, I've noticed a steady accumulation of a thick, black, ink-like soot on the coolant reservoir cap stem. Because it always returned after I wiped it away, I came to suspect that it was due to some chemical reaction the plastic was having with the green coolant. Coupled with the information presented in this thread--namely that Dexcool has a lower alkalinity and the absence of silicates producing a longer service life for water pumps and seals, I'm wondering if this is what the cautionary sticker stating that this vehicle is designed to run ONLY Dexcool means... Moreover, I also see plastic/rubber flakes floating atop the coolant when I have the radiator cap off shortly after turning on the engine to fill the level up to the maximum. Have any of you noticed anything like this in your green coolant?

 

I went GREEN a couple years ago and my temps are absolutely a little better overall. And of course the coolant is always nice and clean.

I never really had any issues with nasty dirty Dexcool, but I just figured I'd switch to Green because a lot of people around my local area said it helped with temps.

.

 

I went with RED. No silicates.

 

In 2007 my 99 TA had radiator, heater core and overflow tank flushed and switched from dex-cool to green universal. Have flushed and replaced the green every three. No cooling issues, heater works perfect, original radiator seems in excellent condition. Me thinks the key with any coolant is change it every few years.

 

Nothing wrong with dexcool as long as its never mixed with any other coolant. It coagulates and plugs up the cooling system quickly when mixed with green and others. I stick with dexcool because I work at a gm dealer and always have extra. My coolant has only been flush maybe twice and at 160k it's still bright orange.

 

My experience with this is with the 3.4L V6 (larger displacement version of the engine seen in video in a post above), car bought new from GM dealer... then at 20K miles the LIMG (lower intake manifold gasket) was leaking coolant inside and outside the engine...

the LIMG is a nylon 6.6 substrate with silicone inserts... both of these materials were attacked ("plasticizing effects" mentioned in a post above) by the factory fill Dex-Cool.

The factory fill Dex-Cool was not contaminated, and there were no air leaks (which is another story for some other GM vehicles that came with leaking radiator caps) in the cooling system (other than the Dex-Cool induced deterioration of the nylon/silicone LIGM).


On your LS engined vehicle, if you ever find an orange colored greasy substance on the front of your oil pan (on the 2 front oil pan bolt heads), it is Dex-Cool leaking out of the water pump, dripping down the front cover, and over time depositing on the bolt heads (when hot in the presence of air it forms a gel, I am told).

 

Prestone makes a green universal coolant that works with DexCool and all other colors. It doesn't necessitate completely flushing out the system before switching over.

 

Has anyone used any of the foreign car, BMW/AUDI antifreeze? I have been considering swapping this in.

 

Hi RP, I too use the BMW "Blue" as I supply/buy from Worldpac.
I use my SpeeDIAL Account to order with my vendor price discount included.
The BMW coolant is made to be Phosphate FREE and is great for areas that have Hard Water.
The Phosphoric Acid will "grap" or bond to particular minerals in water causing large particles to form blocking the radiator core or other ares in the cooling system.

Thus a coolant that is Phosphate Free is my ONLY choice.

Phosphates are use for fertilizer not good for cooling an engine or motor.

Lance

 

We had a water pump go out on the old V6 car our resident college girl is using. The shop found a bunch of black sludge in the cooling system they thought was oil from a bad head gasket. But the car runs fine and passed the exhaust gas test.

Like you say, it was thick and very black. Frankly to me, it didn't look like coagulated oil. More like graphite grease. Don't know what it is. The coolant appears clear, but if you reach into the radiator and touch the metal innards, black soot appears on your finger.

 

I flushed and filled with Euro-spec G-05 on my 02 Formula 7 years ago/5k miles. Coolant is still clear and clean.

 

I use BeCool's pre-mixed antifreeze. It's Propylene Glycol, which isn't supposed to be as good as the Ethylene Glycol stuff, but it works fine for me in hot *** Florida. I don't know how it does in the cold. But I did 2 gallons 50/50 and 1 gallon of distilled.

But the Zerex G-05 looks like the best on the shelf stuff you can buy.

 

Sometimes that oily greasy crap is actually power steering fluid. If the factory power steering cooler is still present, it is known to crack and leak PS fluid into the coolant. Never goes the other direction because PS fluid pressure is much higher.

@Pantera -- thanks for that tip! I'm running water and a surfactant only, but when winter comes back around, that BMW blue makes a lot more sense than anything else.