Can DEX-COOL be used? (Page 1/1)
jumpmonkey AUG 27, 07:39 PM
Can DEX-COOL be used when doing a coolant flush on a Fiero? I've heard stories about newer coolant being swapped into old engines and the detergants/anti-rust formulas not liking each other.
olejoedad AUG 27, 09:13 PM
NO!

If you need to use antifreeze, the yellow UNIVERSAL is your safest bet.
Vintage-Nut AUG 27, 10:26 PM
AND flush the coolant system until the drained liquid is nearly colorless.

Filling Procedure Note:
Keep in mind, the cooling system fluid capacity is 13.8 quarts on the 2.8L V6 and a flushed coolant system can have ~7 quarts of 'water' in the engine block/heater core/etc.
Do Not Use a Premixed 50/50 - pour ~2 gallons (8 quarts) of straight full strength concentrate antifreeze.


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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

Spadesluck AUG 28, 10:02 AM
I am a fan of the green stuff. Never used yellow, so not sure about that. Dex-Cool, not a fan.
Vintage-Nut AUG 28, 10:50 AM
Antifreeze Facts

Antifreeze prevents corrosion, rust and scale buildup, plus helps transfer heat. It also keeps the liquid from freezing and prevents overheating.

But over time, all antifreeze breaks down. The pH balance of deteriorated coolant and the antifreeze depleted corrosion inhibitors become drastically more acidic over time which causes corrosion. Corrosion can ‘attack’ and damage the radiator, water pump, heater core as well as other cooling parts in the system.

Antifreeze vs. Coolant
*Antifreeze is a full strength concentrate solution made of ethylene glycol and corrosion inhibitors.
*Coolant is a blend of antifreeze and distilled water which typically consists of a 50/50 mix, though it can contain more antifreeze up to 70/30 for extreme cold temperatures.

I suggest using pH strips to keep an eye on the coolant and any deteriorated coolant must be entire and fully flushed out of the system.

If you’re in doubt about the ‘health’ of the coolant, completely flush the system.

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GREEN
Inorganic Acid Technology (IAT) is the oldest anti-corrosive blend fortified with fast-acting silicates and phosphates to protect cast iron, copper, brass, and aluminum from corrosion. The Downside: it needs frequent changes (two years / every 30k miles) as it’s prone to flaking and scale formation, especially when used with hard water and dries/corrodes rubber parts. Most US manufacturers stopped using it by the mid-1990s.

{As a Note} The antifreeze spec in your Fiero manual is "Inactive"
GM 1825-M, 6043-M Spec – Inactive / GM 6038M, 1899M Spec – Inactive / GM 6277M Spec – Inactive
If you research, GMW 3420 is the current spec (2017) as "Active" which is Organic Acid Technology (OAT)

YELLOW
Organic Acid Technology (OAT) is either silicate free, phosphate free, or both. The corrosion inhibitors are slower acting but much longer-lived than an IAT. OAT replacement is generally 6-8 years; the maximum is 10 years (or 150k miles). It lasts a very long time and it’s more ecological; the con is that the inhibitors aren’t the best for preventing corrosion. It remains an acceptable coolant and provides good long-term protection but may not be the best choice for copper/brass.

Antifreeze/Coolant Contamination 101
* NEVER mix antifreeze/coolant technologies or avoid mixing brands.
* Mixing IAT with OAT creates a brown nasty sludge.
* When feeling uncertain, thoroughly flush and purge it out!

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Original Owner of a Silver '88 GT
Under 'Production Refurbishment' @ 136k Miles

[This message has been edited by Vintage-Nut (edited 08-28-2024).]