Antifreeze has changed a lot over the decades after the birth of the Fiero, and you guys know way more about antifreeze/coolant than I ever will learn ….
In early of the 21st century, many members were posting that they still use the traditional bright green stuff (GM 1825M spec / IAT) as the ‘best’ antifreeze.
Traditional Green IAT is fast-acting and protects cast iron engine blocks and copper/brass heater cores from corrosion; but IAT needs frequent changes (two years OR every 30k miles) as silicate causes scale in aluminum radiators and phosphate dries/corrodes rubber. Most manufacturers stopped using it by the mid-1990s.
GMW 3420 is the most current spec as Active (2017) which is Organic Acid Technology (OAT) - ethylene glycol based ‘extended life engine coolant’ with a maximum recommended service interval of ten years (or 150,000 miles).
OAT is either silicate free, phosphate free, or both and are slower acting but much longer-lived than IAT antifreezes. OAT corrosion inhibitors provide excellent long-term protection for aluminum and cast iron, but may not be the best choice for older cooling systems that have copper/brass heater cores.
GM OAT-based Dex-Cool which is dyed orange (which has only a few PFF threads) Prestone OAT-based “All Vehicles” which is dyed bright yellow There are green, blue, red, even pink OATs’!
However, I didn’t find current threads (2018 or newer) in the PFF system about the ‘best’ antifreeze type for the present day; i.e. year 2023.
I believe more members are using OAT these days, but I know that my ‘classic truck’ buddies are still using IAT.
This has created some confusion as the type of antifreeze in my ‘88 Fiero…..
Do you still use the traditional green IAT antifreeze in your Fiero?
Did you change to OAT antifreeze?
I’m leaning towards to fill the GT with Prestone OAT-based “All Vehicles” antifreeze however; I wanted to hear from the Fiero ‘gods’ on the forum…..
And YES, I studied and learned the antifreeze/coolant contamination 101: *Don’t mix antifreeze/coolant technologies - NEVER *When in doubt, thoroughly flush and purge it out!
The cooling system fluid capacity of the 2.8L engine is 13.8 quarts; when draining it for the first time, it will measure approximately 7 quarts which means ~50% of the old coolant is ‘trapped’ in the system.
The complexity of cleaning out ALL the old coolant requires many flushing’s until the drained liquid is nearly colorless.
The completely flushed coolant system has ~7 quarts of ‘water’ in the engine block and ‘water quality’ matters! I always use distilled water…
After that, full strength concentrate antifreeze is use to fill the coolant system and the clean recovery tank. VN
When flushing out the cooling system remove the two 1/4 " drain plugs out of the block so the sludge gets flushed out of the low areas around the cylinders. this will get rid of most of the remaining liquid. also drain the coolant pipes with the plugs in front of the rear wheels, coolant catch tank and bottom of rad. If you disconnect heater line at the engine fill you can blow out the heater core and lines. Now you have a clean liquid free system to refill with longlife 50/50. sleek
⚠️ Warning: Do Not use DexCool in cars that have/had Green or other types. GM Never claim DexCool is "better" except in new cars that use it right from the factory. Even factory installed DexCool systems has/had problems.
"Best" now is "universal" coolant often Yellow color from several brand that mix w/ or replace other coolant products. Can still get Green coolant but not sold at most retailers now. Some brands don't even offer Retail Packages of "Old" Green now. Example: Prestone has "Asian" coolant that's Green but likely not same formula as old Silicates Green.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
AS long as its properly flushed Dexcool is fine. I checked with both of our GM dealers in town and both said no problem. They don't use anything but dexcool even on their older trade ins. I have been using dexcool for 30 years now and have NEVER had a problem .
Originally posted by sleek fiero: AS long as its properly flushed Dexcool is fine. I checked with both of our GM dealers in town and both said no problem. They don't use anything but dexcool even on their older trade ins. I have been using dexcool for 30 years now and have NEVER had a problem .
You maybe just got lucky. The Dealers are 100% Wrong.
GM Corp has Many Doc's saying that is wrong. Including Many TSB that many Dealers Ignore.
GM also stated many times installing DexCool in vehicles that had Silicates or other Reduces DexCool to 3 years 30,000 miles. If others are added to Factory DexCool system get same service interval drop. DexCool is famous for plugging the system even on Factory install coolant.
Mr. Ogre ; I am not out to get in a pissing match with you. You can use what you want but there is nothing wrong with Dexcool, Prestone Dex-cool or fords blue version of dexcool. you just cannot run a lead soldered copper rad with it.. it is meant for aluminum or aluminum with plastic tank radiators. As long as the system is flushed well it will perform well.
Originally posted by sleek fiero: Mr. Ogre ; I am not out to get in a pissing match with you. You can use what you want but there is nothing wrong with Dexcool, Prestone Dex-cool or fords blue version of dexcool. you just cannot run a lead soldered copper rad with it.. it is meant for aluminum or aluminum with plastic tank radiators. As long as the system is flushed well it will perform well.
All Fiero and a lot of others have Brass/Copper Heater Cores with Lead base solder. Only those vehicle had the cores replace since Manufacturers comply w/ RoHS maybe have non-lead solder. Old Lead solder replacement cores where still in inventory many years after RoHS and Anti-lead laws/rule. Can still find NOS, used and repaired/rebuild with lead solder. Non-lead solders often have problems on their own w/ or w/o DexCool.
You are right. Thinking about it I changed out my heater core when I got my GT 29 years ago. I guess that's why I have never had a problem with dexcool. Jeez I guess I better drain it out of my 88 Vette too-------NOT.
I checked with both of our GM dealers in town and both said no problem. They don't use anything but dexcool even on their older trade ins.
Dealers are the last to confess of anything negative on their products. The answer is always "yes", no problem.
Case in point,, I converted my Fiero to power steering and use the Toyota MR2 Spyder pump. I also used the factory PS fluid. Years later I decided to pick up some more for shelf stock. The local Toyota dealer never heard of it and said they used regular PS fluid in the MR2's they service. I'd taken a pic of the original container and showed it to them. The 2 of them had a bewildered look on their faces and it wasn't due to the Chinese writing on the can, however the part # on the can removed all doubt.
ps: Beware of Dealers bearing BS.
Spoon ------------------ "Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
[This message has been edited by Spoon (edited 04-18-2023).]
When flushing out the cooling system remove the two 1/4 " drain plugs out of the block so the sludge gets flushed out of the low areas around the cylinders.
got photos of these plugs? When I first got my SE the garbage that came out of the cooling system was amazing.
A year later I flushed it and was amazed how much was still in there, though it was better than before.
The coolant drain plugs on the V6 engine block aren’t 'easy' to remove; one is under the starter. For me, I don’t remove the starter for a 'normal' preventive antifreeze/coolant flush.
Others have commented that removing the engine plugs are ineffective besides as considerable amounts of coolant can remain in the engine block. If you use ‘hard’ water in the system, yes, of course you will have more ‘junk’ to flush out….
When I drain the coolant system, I don’t get any ‘garbage’ in the container, only the coolant. Perhaps this is because I completely flush the engine ten times with distilled water before pouring-in full strength concentrate antifreeze. Yes, this takes some time to fill/run/cool/drain repeatedly until the drained liquid is nearly colorless.
This is the main reason I started this thread as IAT antifreeze needs more frequent changes...... VN
For me, I don’t remove the starter for a 'normal' preventive antifreeze/coolant flush.
For a standard change, I wouldn't either. Last two changes I popped out the fittings on the coolant tubes running along side of the car, and then put a hose in the fill tube and let it cycle for a while.
With the amount of garbage that came out the second time, it would not surprise me if there was a ton of additional garbage that a regular flush didn't touch.
Though, if I have to remove the starter to get to that plug, maybe I'll roll the dice and just not. And, the other is on the firewall side, I'm assuming?
Yes, Can remove engine plug(s), If can find or have access to it/them. V6 maybe easier in Pic above but in the car may depend on trans and other things. Example: Auto trans and exhaust make hard to just see anything on rear side of V6. Front side have similar problems.
I think L4 has only one... Above the starter there is 1 plug but this is 1/4" square hole type on mine. Can reach from the top. Tries to hide under the "recall shield" sandwich between block and exhaust that covers most of front of head and block. Problem is do not let coolant or water to run on/in the starter and solenoid. Water is bad enough but Coolant is very conductive and could "short out" the big battery cable. Doesn't have a drain on rear side.
Even if you find and remove the engine drain(s). The Block, Rad and other things still have enough water to never use 50/50 mix to fill after flushing. Many would loosen/remove a low hose to drain the rad before messing w/ easy to break drain plug on that. Even if used, Fiero "tipped" the rad so can't total drain it.
The coolant drain plugs on the V6 engine block aren’t 'easy' to remove; one is under the starter. For me, I don’t remove the starter for a 'normal' preventive antifreeze/coolant flush.
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by sleek fiero I was just explaining how to do the job properly. It is up to each car owner to decide whether they just want to do a half assed job or not.
So, in your view, "properly" means removing the starter for a 'normal' preventive antifreeze/coolant flush....
that's the way the gm service manual says it should be done . You only need to do it every 3-4years.unless the test strips say to do it sooner. The thing about bad coolant is it's usually too late by the time it leaves you stranded beside the road the damage is done.
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