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Unread 01-23-2015, 03:20 PM   #1
01Mastiff
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What's the deal with HOAT and OAT

I know you can't mix 'em. Have a 2014 JKU and wondering why these (Chrysler) are the only engines requiring one of these two. Hundreds of millions of cars are out there running on Peak or some other 50/50 which doesn't run the risk of turning into sludge and screwing your engine. I use Peak in some of my cars and Evans in the performance cars. What is so special about Jeep engines that they have to use this stuff. Can't I just drain this stuff out, flush and use an "easier" coolant?

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Unread 01-23-2015, 04:12 PM   #2
kik
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I wouldn't unless you want a warranty issue. That's the way they designed the system, HOAT or OAT. You can find aftermarket equivalent coolant that conforms to spec. Some aftermarket coolants will degrade the gaskets in these engines. After reading tons of posts over the years I've decided to use the Mopar coolant which is called for and call it a day. I know what you mean though, because I also have an Xterra that came with 5yr. coolant. Nissan 10 yr. extended life coolant is compatible with their shorter life coolant so you can mix and match all day with zero issues. I switched to extended life with no issues. I don't understand why Chrysler couldn't have done the same.
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Unread 01-24-2015, 10:41 AM   #3
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First off Chrysler is NOT the only one requiring one of these two. Dex-Cool (GMs "required") is the original OAT formulation as introduced. HOAT and OAT play well together - HOAT and EG make sludge, OAT and EG increase corrosion. The three together will ruin your cooling system - you may just dump flush and fill with whatever you want - but WHY? The formulation does brings something to the table - service life, corrosion and electrolysis control and toxicity to animals for just a few positives (oat and hoat do not smell attractive to animals - EG attracts dogs and other pets like kids to candy and kills dogs dead). But sadly that means DIYers must think for themselves more - or hand off the maintenance at a cost.

But I do agree - the darn engineers should just leave well enough alone. I feel we should all still be pulling a knob to reduce ignition advance and watching with glee as our wife cranks the 4 cyl flat head - for fun we can even add the timing back mid stroke and see if it will toss her about ten feet when it kicks back. Then we should light the carbide in our head lamps at dusk, crank the wipers by hand etc. I mean if it worked in 1920 why the hell did we change it?
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Unread 01-24-2015, 04:50 PM   #4
01Mastiff
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According to Chrysler Tech Manual is the following warning regarding mixing of HOAT and OAT coolants: "THESE TWO COOLANTS DO NOT MIX, AND A CHEMICAL REACTION WILL CAUSE IT TO GEL." Which would tend to indicate to me that they in fact, do not "play well together". My original point being if I take my vehicle into anywhre for anything and someone in the shop decides to do me a favor and top off my coolant I could be screwed. Neither of these coolants is anywhere near the state of any art. Evans coolant lasts a lifetime, has no corrosive properties even in aluminum engines (I've been running it in my aluminum 427 pushing 1,000 hp for years) and will not boil. If HOAT was doing such a bang up job, why is the Jeep factory adding stop leak on the production line? I have owned over a hundred cars in the past 50 years (one going over 350 thousand miles without engine work) and have never had a coolant failure resulting in engine damage or corrosion of any seal or part. I have also never had any dogs die from antifreeze and of all the things that have damaged the environment antifreeze is low on the list. I still kick start my '47 Harley and in general am fine with things the way they were.....before my coolant could turn to "gel".
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Unread 01-24-2015, 07:26 PM   #5
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Quote:
Originally Posted by jwmbishop View Post
First off Chrysler is NOT the only one requiring one of these two. Dex-Cool (GMs "required") is the original OAT formulation as introduced. HOAT and OAT play well together - HOAT and EG make sludge, OAT and EG increase corrosion. The three together will ruin your cooling system - you may just dump flush and fill with whatever you want - but WHY? The formulation does brings something to the table - service life, corrosion and electrolysis control and toxicity to animals for just a few positives (oat and hoat do not smell attractive to animals - EG attracts dogs and other pets like kids to candy and kills dogs dead). But sadly that means DIYers must think for themselves more - or hand off the maintenance at a cost.

But I do agree - the darn engineers should just leave well enough alone. I feel we should all still be pulling a knob to reduce ignition advance and watching with glee as our wife cranks the 4 cyl flat head - for fun we can even add the timing back mid stroke and see if it will toss her about ten feet when it kicks back. Then we should light the carbide in our head lamps at dusk, crank the wipers by hand etc. I mean if it worked in 1920 why the hell did we change it?

love the sarcasm! couldn't have put it better. Started posting much the same yesterday then decided that some just want to vent and not open to newer technologies! Maybe OP just wants to plug specific aftermarket brands?

just a small correction: OAT is the loner that doesn't like to play. Nothing except OAT mixes well with OAT. The latest Mopar OAT is rumored (by those in the coolant world) to be the same blend as the latest DEXCOOL blend (as it was modified over the years) .

ANY conventional coolant will mix with HOAT (but will reduce it's extreme properties to that of a conventional coolant.

As for durability of components: been in the buissness long enough to be able to claim that the corrosion/blockage problems of the past (1980's technology) are few and farther between with the newer technologies. All due to antifreeze and better alloys? probably a bit of both.

Some of this, I assume, is also proprietary branding for profit, but also for quality control- a common standard or control over the quality of aftermarket suppliers (they need testing and licencing to be approved)






Quote:
Originally Posted by 01Mastiff View Post
My original point being if I take my vehicle into anywhre for anything and someone in the shop decides to do me a favor and top off my coolant I could be screwed.
THERE YOU GO! jack of no trades if they can't tell or don't know the PROPER repair parts and procedures for a particular vehicle.... the times of opening the hood to anybody are things of the past.
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Unread Yesterday, 10:05 AM   #6
jwmbishop
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Quote:
Originally Posted by 01Mastiff View Post
According to Chrysler Tech Manual ..... still kick start my '47 Harley and in general am fine with things the way they were.....before my coolant could turn to "gel".
It's funny that the people who make the stuff say one thing and Chrysler says another... Possibly the pellets + hoat + oat is the villian. Then lets not even get started on DEF - glad the jk ain't a diesel. Who knows what we would have to stuff in it!
I get it that when you buy a uniquely engineered vehicle - you can expect to have specific requirements. My v series is very particular on what goes in its cooling systems... the jk aint that though which is what makes the issue such a slap in our faces. it is a let down that Chrysler gave us such a hearty utility vehicle that will burn the gas from any pump - yet can't use that anti-freeze on the shelf at Billy bobs middle of nowhere fuel stop...
And my opinion is that if i take it to some idiot that screws it up - I chose the wrong idiot...
Last of the knuckles - hang on to that one. I could barely kick one in my youth. course I was okay as long as my ex was around - she could draw start it from the tail pipe ... even with a burnt valve and fouled plugs...
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Unread Yesterday, 10:41 AM   #7
FJ55guy
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Definitely dont want to mix your HOAT and OAT, first thing they tell you in tech school. They say a cup of the Oat in the Hoat can gel the entire systems.

However, jwmbishop hit the nail on the head, Chrysler is far from the first ones to introduce a system specific coolant.
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Unread Yesterday, 11:34 AM   #8
14Sport
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Originally Posted by jwmbishop View Post
she could draw start it from the tail pipe ... even with a burnt valve and fouled plugs...
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Unread Yesterday, 12:49 PM   #9
jwmbishop
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Quote:
Originally Posted by FJ55guy View Post
Definitely dont want to mix your HOAT and OAT, first thing they tell you in tech school. They say a cup of the Oat in the Hoat can gel the entire systems.

However, jwmbishop hit the nail on the head, Chrysler is far from the first ones to introduce a system specific coolant.
That's a good safety rule. Because SOME oats will sludge up in SOME hoats... and all oats will sludge up in most IATs avoiding mixing altogether is the safest way.

Antifreeze has traditionally been ethylene glycol (EG) with Inorganic Acid Technology (IAT) corrosion inhibitors added since 1926. (and closed - pressurized - systems were developed in 32-34).
American vehicles have traditionally been designed to use antifreeze with silicates and phosphates as corrosion inhibitors.
European vehicles have traditionally used antifreeze that does not use phosphates.
Japanese vehicles have traditionally used antifreeze that does not use silicates.
Newer corrosion inhibitor technology includes Organic Acid Technology (OAT) and Hybrid Organic Acid Technology (HOAT). Both may be referred to as “extended life” antifreeze and were introduced in the 1990′s and use propylene glycol (PG).
IAT antifreeze has a 2 year or 30,000 mile service life, where OAT and HOAT have a 5 year or 150,000 mile service life.
OAT based antifreeze is not compatible with IAT antifreeze; although, some HOAT formulas claim compatibility with certain OAT formulas or IAT formulas.
OAT and HOAT antifreeze is designed for use in aluminum radiators and components. You should NEVER mix OAT based formulas (which includes hoat) with IAT formulas. The result is typically turning your coolant into sludge due to a chemical reaction. Keep in mind, OAT based formulas are still a developing technology. There are some “universal” formulas that claim compatibility with other IAT and OAT formulas, but the only safe bet is to use the same formula that is already in your vehicle. This may change as the OAT based formulas continue to develop; however, always err on the side of caution and use the same type of formula that the manufacturer recommends.

See why the "safe" rule is best - and should be taught to every tech?

If you were designing your own system the rules are REAL simple:
If you have a mix of cast iron, aluminum and ANY brass in the system (old school radiators) - do not use oat or hoat - use IAT (ethylene glycol). propylene glycol does not do well controlling electrolysis in a three metal environment (or even a two metal when one is brass)- and can actually speed up the process of molecular distribution. The organic additives actually help carry the brass molecules trying to swap places with the iron.

If you have an cast iron\aluminum system - never use IAT - use oat (hoat as second choice). This is where Dex-Cool was designed - for the cast block aluminum head GM engines.
If you have an all aluminum system - again no IAT - use HOAT (oat as second choice).
Anything organic can be broken down. With Organics the additives becomes more sacrificial than the metal surfaces - that is they break down before they can piggy back the metallic molecules attempting to be transferred via electroysis. Mixing organic (PG) with inorganic (EG) - causes the organics to break down faster, fall from suspension at the molecular level AND the inorganics to attach to them. Sludge.
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