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COOLANT CONFUSION: IT'S NOT EASY BEING GREEN ... OR YELLOW OR ORANGE OR ...

Skydrol

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Interesting read, knowledge is "power" (pun intended).


What's In DexCool?

You should know that the term "orange coolant" has come to mean a DexCool-approved brand but that doesn't mean it's really true. If you make this assumption, you'd be wrong. It's what Ford's warning labels could be interpreted to refer to, so that label doesn't serve to clarify things (certainly not when a Ford system contains a very different-non-DexCool, but orange-dyed-coolant). The discontinued Mercury Cougar was an exception; it did contain an orange coolant similar to DexCool.

The "DexCool" designation means the coolant passes General Motors performance testing. Although DexCool is not a specific formula, all three brands that have the label (Texaco Havoline, Prestone Extended Life and Zerex Extended Life) are somewhat similar. In particular, they're OAT coolants, but the similarities go beyond that basic description.

All DexCool-approved coolants to date use two organic acid rust/corrosion inhibitors, one called sebacate, the other called 2-EHA (which stands for 2-ethylhexanoic acid). These organic acids are very stable and last a long time, although they take thousands of miles to become fully effective in protecting coolant passages.

GM recommends a DexCool change every five years or 150,000 miles, whichever comes first. Because most people drive 15,000 to 20,000 miles a year, that translates to a five-year replacement interval. As noted, the thousands of miles required to protect metal is an important trade-off for that longer life. Although like conventional coolants, OATs also contain other inhibitors, for targeted protection.

The inhibitor 2-EHA works well in hard water and is more effective than sebacate at lower pH levels (when the coolant moves from the alkaline end toward the acid side), particularly for cast iron. Well, GM has a number of cast-iron engines. When there's a low coolant level in the coolant passages, the exposed cast iron rusts. Apparently, that rust is washed away later by flowing coolant, and is deposited in the heat exchangers. It eventually produces the rust powder problems that have been so widely observed (see Motor's August 2002 issue at www.motor.com). Why does the coolant level in these engines drop? The original radiator cap design was blamed for some of the issue, but there probably are a number of causes, including owner neglect and normal seepage. However, the rust powder issue is not a problem that was observed with the previously used conventional American coolant.

The inhibitor 2-EHA poses another issue: It's a plasticizer (softens plastic), so it has been blamed for coolant passage gasket leakage. Softening (and the resulting distortion) was reported by Ford, which encountered gasket leakage problems when it tested a DexCool-type formula on its V8 engines. Ford also saw similar issues with other gasket materials. That killed the OAT coolant idea for Ford, which had used a DexCool-like coolant in the '99 Cougar V6.

Could that inhibitor be responsible for the intake manifold coolant gasket leakage on GM 60� V6 engines? Or is there some other service issue involved? (After all, GM isn't the only one with coolant gasket leakage problems.) The experts are still working on it.


There is way more information in the article.
https://www.motor.com/magazine-summ...-not-easy-being-green-or-yellow-or-orange-or/
 

immortality

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Not to be picky but isn't Dexcool red?
 

Skydrol

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Well, is up to interpretation, looks like Terracota to me, between red and orange.
 

RiCeY

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More orange, Fortron coolant is red.
 

Skydrol

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It taste really awful. One time a drop got on my lip, got a "taste" of it.... my god, is really bad. The regular Coolant was very sweet, I see why they added some that taste bad to prevent pets drinking it.
 
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DAJOKER

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Ok heres a question.

VE LLT engine - Im doing some manifold spacers, and while the manifold is off, Im going to change the entire thermostat housing. (had the car since new, 160***km, bit of preventative maintenance)

This is from revhigh.com.au
- It is strongly recommended that genuine parts be used for this job. The pipes coming out of the housing are sealed with O rings that if not the correct size down to thousands of an inch will more than likely leak. We advise buying the genuine housing, thermostat and O rings.

Whilst doing this job we also strongly recommend you carry out a cooling system flush and changing the coolant from the factory red to green coolant. Make sure a full flush is done including the heater core. We have found the red coolants are more prone to leaking than the green ones. -

so - RED or GREEN.
 

Skydrol

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Color is just a dye, all boils down on what chemicals are in the mix and what ratio. I have used Dexcool with great success. The key is to avoid air pockets in the system. So keeping an eye on will ensure reliability.
 

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I think revhigh have no idea what they are talking about.
 

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I ran Prestone dexcool in my old VN and never had issues but then checking coolant level was a simple visual check of the expansion tank so no exposure to air. Cooling systems that use a recovery type expansion system that is open to air I'm not so sure about.
 
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