Which coolant???????

[73k5blazer]

In the old days, there was only one. Then GM changed things up with their OAT formula in the mid 90's. Some say it's junk, others say it's fine.
Ford and Chrysler specify yet another coolant, G-05 a HOAT formula. (Hybrid OAT).

It seems the Dexcool stuff GM has been using contains an ingredient called 2-EHA , which from what I read , doesn't like air. The fact that GM has switched to a pressurized coolant bottle with the rad cap there instead of on the radiator, is proof enough of that, that and their TSB's on various customer complaints about dexcool gumming up has boiled down to an air leak somewhere, like a loose or ill-fitting rad. cap .

I've done extensive research around this for the last couple months. Read ALOT of techical articles, I'm still somewhat undecided as to which coolant I should really use in my Cast-iron RamJet engine, with aluminum radiator and alum. heater core. I've had Dex-cool in my 1970 impala with original 60kmi 400sbc engine for 4 years now, still looks perfect. I only used it because I had a fleet of newer GM vehicles that specified it and I didn't even think twice about it at that time. But I don't think it has an issue with air in that car, there's no overflow bottle. so any coolant exposed to air is simply expelled out to the ground and not re-introduced to the system. In my K5, there's an overflow bottle (I don't particularly like dripping coolant on a hot day after you shut your car off).

G05 is low silicate, which implies lower protection for alum. radiators. ,it does have a decent phosphate does (which I think is good protection for alum?) although it says it's fine for alum & cast iron parts.
Green stuff is supposedly bad for bi-metal engines, turns into a battery pretty quickly, from what I gather.

I'm somewhat inclined to go with the G05 stuff, but it does not meet any GM specification. These Ramjet engines are same parts, seals, gaskets and all, for lots of late 90's early 2000's GM engines before they got rid of the old SBC block for good. So I'm a little afraid the G05 stuff may not play well with certain seals and whatnot.

So, what do you all use for any cast-iron alum mix in your cooling system?

 

[Fordum]

Well, you could always go with this stuff and avoid the whole thing......

http://www.evanscooling.com/

Friend of mine has it in his Diesel and loves it. I think he has about 120K on it now. It looks nasty after a few thousand miles, but he has never changed it.

 

[dyeager535]

Admitted I haven't done a ton of research on coolant, but that is partly because there is so much anecdotal evidence, BS, and overall contradictions that it's hard to find actual facts.

I've got green stuff in mine (AL intake, copper/brass radiator, iron block) and I'm not real happy with the corrosion I'm seeing in the radiator, especially since as far as I can tell, the anti-corrosion properties in the green stuff decline with use. The truck doesn't see much use.

When I move my radiator, perhaps I *will* go the surge tank route and run dex-cool. Was somewhat hoping to avoid having to do that, plumbing one would seem to be a bit of a pain.

 

[sweetk30]

also best to run distilled water for best starting point.

and as a mechanic for years hell if my own money will ever buy dex crap

 

[6872xtc]

I don't have any help as far as green vs. dex-cool. I can tell you that the Evans coolant is so far for me worth the money. It will scare the crap out of you when you look at the price and the fact that you do not dilute it. (more gallons to fill the system) The reasons I bought it for my big block truck was the cooling power they claim and the fact that my truck sits a lot, so no water, no corrosion helped sell me. So far five years and only 7K or so and I don't see any signs of corrosion in the cast iron parts or the aluminum radiator. I can tell you that I have no heat problems, even with the A/C.

 

[sweetk30]

guy i use to work on his truck for was a super crazy reserched every thing kind of guy .

he had a 7.3 in his ford f250 and that was a drink and a half to fill up.

he purchased this evens cooling stuff. and if i recall no pressure in the system also . so no psi blow outs to have hanging over your head.

 

[6872xtc]

Ooops! yeah I forgot that! I have a 5 psi cap now. The guy at Evans told me that was to keep it contained was all, as no pressure needed for advertised boiling point.

 

[Fordum]

Yeah, my friend was showing his engine to me, and it was at operating temp. He just took a rag and reached out and took the radiator cap off.

I been around things like that waaaay too long. Even with my bad leg, I was 15 feet away before he finished taking it off.
But there was no pressure. He had even drilled a small hole to let any pressure out.

Said the only thing that could build up pressure was water, and you wanted all of it out.
With the vent hole, it would eventually all escape as vapor.

 

[nsxxtreme]

The green stuff eats aluminum from my experience. My range rover which is an all aluminum engine uses a blue BMW coolant but I don't know what's significant about it. If you find some good information please share with the rest of us.

 

[1BEATK5]

that blue coolant is oat with a blue dye added.

to the op. hoat or oat would be fine. either one is way ahead of old green. i have seen alot of issues fixed by switching to hoat in chrysler products. i plan on doing it to my xj when the radiator starts leaking. i would just pick what brand you want and stick with it.

chrysler is finally going to oat in 2013. the new dart has it. all others will switch soon. its the same formula fiat uses. but its going to be purple. it looks like koolaid.

we had a regular customer that had a 99' grand cherokee with a 4.7 v8. still green coolant. hoat didnt come out until 02". we replaced the radiator because it was plugged. i pulled the tanks off and found the usual white crystal crap plugging the tubes. he came back about 10 times after that. every 3000 miles we put a radiator in it. most where mopar, but some where aftermarket. the tubes would corrode and leak. after a few phone calls to engineering about it, they had me check the voltage of the coolant. it had over 4.5 volts in the coolant. so the last time it was in i drained the block, flushed the heater core, replaced the timing cover and refilled it with hoat. he hasnt been back for a radiator since.

 

[nsxxtreme]

that blue coolant is oat with a blue dye added.


they had me check the voltage of the coolant. it had over 4.5 volts in the coolant. so the last time it was in i drained the block, flushed the heater core, replaced the timing cover and refilled it with hoat. he hasnt been back for a radiator since.

What the heck is oat?

I know the Range Rover dealer wanted $40/gallon since my truck was made by BMW I went to the BMW dealer and it was $20/gallon. Most parts I don't even bother with the RR dealer. Just find the cross reference of the part from RR to BMW and the cost is about 1/2. Just goes to show the RR is a seriously over priced rig.

The voltage thing can cause corrosion big time. If you store a boat your supposed to disconnect the battery to prevent corrosion. Head gaskets supposedly go quickly if you leave the battery connected.

 

[CGT80]

I run the green prestone in my 79 with a 406 sbc that has aluminum heads, intake, and water pump. The engine is designed to make 525 tq at 3500 rpm 470 tq at 2000 rpm, and 420 hp at 5000 rpm. The radiator is brass or copper. It seems to be ok, but I would like to keep my temp as low as possible. I notice a big performance loss above 180f coolant temperature. I still haven't finished setting up my mechanical advance in the msd hei dizzy. I need to slow down the curve a bit. I had it much faster before, and the extra advance really added extra heat to the engine.

I am not sure if my tuning is just off for a higher coolant temp, or if this engine just likes to run cold. My tbi 350 (less than 1,000 miles on a new gm goodwrench engine) k5 runs just fine at 210, but it was designed for that and is computer controlled. It also has half the power of the 406, and feels a bit anemic all of the time.

My uncle is a mechanic and hates the red gm coolant. He said it eats up the heater cores. A heater core replacement in a 2005 chevy pickup with a 5.3 is about $1700. My brother did it himself and spent 7 hours at it. The shop book the dealer used says 8 hours. You have to pull the entire dash, and then also recharge the AC after breaking loose those lines.

 

[dyeager535]

Well, you could always go with this stuff and avoid the whole thing......

http://www.evanscooling.com/

Friend of mine has it in his Diesel and loves it. I think he has about 120K on it now. It looks nasty after a few thousand miles, but he has never changed it.

Right on Evans website if you read into the coolant (http://www.evanscooling.com/how-it-works/maintenance), they talk about 27% increase in flow being necessary for it to meet the same heat transfer of Ethylene Glycol/Water. The assumption on Evans part is that you are most definitely boiling the coolant in the system...that's an assumption, not fact.

While I won't throw Evans under the bus, I've never run it. But at $40/gallon, I don't see why I'd even attempt to run it...I'm not interested in having to increase flow 27%. Because *I'm* assuming my engine doesn't boil the coolant excessively.

I suspect their statement is more directed at applications where out of control boiling is a fact, not just an assumption, in which case the benefit is obviously there. If you do more research on Evans online, you'll see folks who have both good and bad experiences...which leads me to believe that under harsh conditions, Evans can be a benefit. But when the cooling system is up to the task, it could cause problems.

I believe the real concern with Evans would be when you are running a properly sized cooling system, but just barely. That 27% difference would put you over the top. Since I intend to run a smaller radiator, in my mind, running Evans would be a gamble, and an expensive one at that.

Good coolant and air flow, good radiator, you shouldn't need it. For the corrosion portion, that's another matter. I would certainly love to run something that completely eliminates all the nastiness that happens in the cooling system, but without the downsides of antifreeze.

I should point out, to clarify my previous statement about the green stuff in my system being disappointing, that I run the minimum recommended level of antifreeze (30%) and that may be influencing what I am seeing.

I will see if I can find out if you can run water, water wetter, and antifreeze together. Only reason I run antifreeze is for what it's good at, keep it from freezing, if I didn't have to worry about that, it would be water plus an anti-corrosion additive like water wetter.

As to OAT and HOAT...are there any things that causes problems with it?

I see the comment on Dex Cool and air, I don't quite see how any system is isolated from being exposed to air, the overflow tank is exposed to air at all times, any coolant going in there will be "contaminated".

 

[6872xtc]

Holy crap! Evans is up to $40/ gallon!!! Anyway, what I understood was that Evans needs more flow, but it has higher surface tension??? As in it transfers heat without the micro (?) boiling at the cylinder surface.

Could someone please give a quick explanation of OAT and HOAT?
Thanks

 

[dyeager535]

Like this helps: http://en.wikipedia.org/wiki/Antifreeze#Organic_acid_technology

I knew it was something organic acid, there you go. As you can see, there is/was all sorts of controversy about Dex-Cool, so who to believe? If you believe GM, it was stupid owners (ok GM didn't say that, did). I tend to think GM is probably correct.

My opinion is that running water, minimum antifreeze required, and a product such as water wetter is the best bet. This and the below are all under the assumption that your cooling system is adequate, and already in good shape.

Straight water is the best coolant available (strictly speaking in terms of heat transfer) undoubtedly. But it freezes and helps promote corrosion. Yes, it boils, but that is why the system is pressurized. A 15+ PSI radiator cap raises the boiling point of STRAIGHT water beyond what any motor should run.

Use the minimum percentage of antifreeze required to prevent freezing in any climate your vehicle will experience. The *antifreeze* properties of coolant DO NOT change/degrade, so replacement is unnecessary for freeze protection.

Running a product such as water wetter introduces the anti corrosion additives and lubricants necessary to keep your coolant system happy. It is compatible with glycol. Therefore, you could run say water, 30% antifreeze (if your vehicle doesn't see temps under roughly 5*F), and a bottle of water wetter, and satisfy all the requirements of a coolant for our trucks.

To be clear: Water is the best heat transfering fluid we have ready access to. The higher the percentage of WATER in your cooling system, the less work your other cooling system components (radiator, fan, water pump) will be required to do.

Most applications require freeze protection, which means some antifreeze. Use the minimum necessary. When running minimal antifreeze, I believe (based on my experience) that additional anti-corrosion additives are beneficial, and a smart way to go. Running the least amount of antifreeze necessary for your climate saves money, is theoretically better for the environment, and your cooling system is more effective.

http://www.valvoline.com/pdf/zerex_original_green.pdf
Note that corrosion inhibitors (what wears out in antifreeze) are only 2% of the total of that antifreeze. Boilover ratings are at 15PSI, which would be roughly 250* for straight water under that pressure. Boilover claims dishonest or just misleading? Your call.

http://www.magers.org/handy/antifreeze.html
Don't know what antifreeze that the chart is based on, but I notice that the freeze protection numbers match the Zerex numbers, and that Zerex does not list the 30% figures, which they used to.