HOAT antifreeze

[manyhp]

I'm changing my coolant and a bit puzzled by the HOAT specification. How critical is this? I was planning to use Fleetgard EG Complete propylene glycol. but the "HOAT" spec concerns me. Also has anyone had a problem with the radiator draincock?

 

[Bill Stockard]

You need to review the article "Antifreeze for Your Truck" in Issue 62, pages 42-44 before making a decision on a replacement coolant.



Bill

 

[gtobey]

I'd stick with the HOAT, for several reasons. One of which is when you change it, you just can't get it all out. Secondly, if you stay with the HOAT you can go longer between changes. And thirdly, you'll keep the protection already provided with the additives in the HOAT protecting your heater core, water pump, etc... read on:



From Wikipedia:



Most commercial antifreeze formulations include corrosion inhibiting compounds, and a colored dye (commonly a green, red, or blue fluorescent) to aid in identification. [10] A 1:1 dilution with water is usually used, resulting in a freezing point in the range of −35 °C to −40 °C, depending on the formulation. In warmer or colder areas, weaker or stronger dilutions are used, respectively, but a range of 40%/60% to 60%/40% must be maintained to assure corrosion protection and optimum freezing prevention.



Glycol antifreeze solutions should generally be replaced with fresh mixture every two years.



Organic acid technology

Certain cars are built with Organic Acid Technology (OAT) antifreeze (e. g. , DEX-COOL), or with a Hybrid Organic Acid Technology (HOAT) formulation (e. g. , Zerex G-05), both of which are claimed to have an extended service life of five years or 240,000 km (150,000 miles).



DEX-COOL specifically has caused controversy. Litigation has linked it with intake manifold gasket failures in GM's 3. 1L and 3. 4L engines, and with other failures in 3. 8L & 4. 3L engines. Class action lawsuits were registered in several states, and in Canada, to address some of these claims. The first of these to reach a decision was in Missouri where a settlement was announced early in December, 2007. Late in March 2008, GM agreed to compensate complainants in the remaining 49 states.



There are rumors that mixing DEX-COOL with standard green (non-OAT) coolant causes a chemical reaction that produces sludge in the cooling system. According to the DEX-COOL manufacturer, however, "mixing a 'green' [non-OAT] coolant with DEX-COOL reduces the batch’s change interval to 2 years or 30,000 miles, but will otherwise cause no damage to the engine. "



According to internal GM documents, the ultimate culprit appears to be operating vehicles for long periods of time with low coolant levels. The low coolant is caused by pressure caps that fail in the open position. (The new caps and recovery bottles were introduced at the same time as DEX-COOL). This exposes hot engine components to air and vapors, causing corrosion and contamination of the coolant with iron oxide particles, which in turn can aggravate the pressure cap problem as contamination holds the caps open permanently.



Typically OAT antifreeze contains an orange dye to differentiate it from the conventional glycol-based coolants (green or yellow). Some of the newer OAT coolants claim to be compatible with all types of OAT and glycol-based coolants; these are typically green or yellow in color.



Additives

All automotive antifreeze formulations, including the newer organic acid (OAT antifreeze) formulations, are environmentally hazardous because of the blend of additives (around 5%), including lubricants, buffers and corrosion inhibitors. Because the additives in antifreeze are proprietary the material safety data sheets provided by the manufacturer list only those compounds which are considered to be significant safety hazards when used in accordance with the manufacturer's recommendations. Common additives include: sodium silicate, disodium phosphate, sodium molybdate, sodium borate, dextrin (hydroxyethyl starch), and a green dye, disodium fluorescein (dyes are added to antifreeze to help trace the source of leaks, and as an identifier because the different formulations are incompatible).



Automotive antifreeze has a characteristic odor due to the carcinogenic additive tolytriazole, a corrosion inhibitor. The unpleasant odor in industrial use tolytriazole comes from impurities in the product that are formed from the toluidine isomers (ortho-, meta- and para-toluidine) and meta-diamino toluene which are side-products in the manufacture of tolytriazole. These side-products are highly reactive and produce volatile aromatic amines which are responsible for the unpleasant odor.



Visit this website to decipher the different chemistries of replacement antifreeze.

http://www.valvoline.com/pdf/Zerex_CoolantChart.pdf



Zerex G-05 is the recommended replacement from Valvoline.



Here's what the filter manufacturers council says about mixing OAT with HOAT. Color of Antifreeze. "It is recommended that OAT not be mixed with any other antifreeze technology. "



I know it's a lot of information, however, what it is saying, is to use the right stuff to prevent future problems... . If you have the HOAT, put HOAT back. If you flush the system with distilled or deionized (no minerals) water several times, including the heater core, you may get about 75% of the old out, and up to 90% if you use one of the flushing machines on the market. So it is easier to just drain it, replace the thermostat while there, and fill it up with the 50/50 premixed so that you will return it back as closely as you can to the protection provided originally. Then you won't have to worry about it for a long time again...

 

[Bob Cochran]

As to answer the question about if anyone having problems with the drain plug, YES. Most of us have I know on mine I thought was going to break it for sure but did not. Almost everyone thinks you should have a spare O-ring in case it starts leaking when you close it. The last time I changed anti-freeze I just took off the bottom radiator hose dumping into an old wash tub,little messy. I was replacing hoses anyways but I think will do it that way again. I just sure going to break that drain plug.

 

[JohnBoy5]

I did tons of research and the Zerex G-05 is the only thing i am going to run for now on! it's some good stuff!



this thread might help also. its one i started when my water pump started leaking.



https://www.turbodieselregister.com...998-5-2002/223440-i-need-antifreeze-help.html



make sure you flush the system really really good to get any old stuff out. heater core also!!!

 

[JohnBoy5]

As to answer the question about if anyone having problems with the drain plug, YES. Most of us have I know on mine I thought was going to break it for sure but did not. Almost everyone thinks you should have a spare O-ring in case it starts leaking when you close it. The last time I changed anti-freeze I just took off the bottom radiator hose dumping into an old wash tub,little messy. I was replacing hoses anyways but I think will do it that way again. I just sure going to break that drain plug.

I could turn mine but i could not get a single drop out of it. is there a trick to this madness like pull out or something. i too took the lower hose off and even pulled the radiator out to clean the cooling fins and flush that out also.

 

[AH64ID]

Unless you can do a 100% flush you need to run HOAT. I used more than 20 gallons of distilled water flushing mine and still wasn't clean enough to run anything but HOAT.

Here is my write-up

https://www.turbodieselregister.com...s-2003-2007/218402-coolant-flush-3rd-gen.html

 

[Bob Cochran]

Turn and pull out I thought for sure mine would break it was so hard to pull out.

I could turn mine but i could not get a single drop out of it. is there a trick to this madness like pull out or something. i too took the lower hose off and even pulled the radiator out to clean the cooling fins and flush that out also.

 

[JohnBoy5]

thanks, i played and played with that thing when i flushed my last time. i was worried about breaking it and so i stopped. i jsut tool the lower hose off. i will remember that for the next time.

 

[Bob Cochran]

Mine did not break but others have broken it so wish you the same luck I had.

 

[JohnBoy5]

i may need the luck sometimes i cant jsut leave something alone. even though i did my flush with out i plan to try and get it to open this weekend. lol

 

[rbattelle]

I'm changing my coolant and a bit puzzled by the HOAT specification. How critical is this? I was planning to use Fleetgard EG Complete propylene glycol. but the "HOAT" spec concerns me. Also has anyone had a problem with the radiator draincock?

I did this in 2004 with under 12k miles on the truck. Fleetguard Compleat ES PG premix. 6 years and about 70k miles later the coolant looks exactly the way it did the day it was filled. Highest ever coolant temperature in the intervening years was between 196°F and 198°F. Lowest coolant temperature was somewhere between -8°F and -12°F. No cooling system service has been performed since the changeover, except I've added small amounts of ES Compleat extender chemical every couple years. (I've added less than 1 quart total extender chemical over these past 6 years, and it's mostly to make me "feel" better).

I had it done incompetently by the local Cummins shop, and they didn't completely drain out the old HOAT.

Fleetguard says they know of no chemical incompatibilities between their Compleat line and any other commercially available antifreeze.

-Ryan