Mixing different brands of coolant

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I just stumbled onto a warning in my Honda service manual that says:
CAUTION: Do not mix different brands of antifreeze/coolant.
I have a feeling that this warning is not observed by most independent
shops and Honda owners over the life of a car. So I wonder what kind of consequences might one expect from mixing different brands. Don't they all use essentially the same ethylene glycol?
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Yes, but the rest of it is different from brand to brand, not all of which are compatible with each other.
And since you have no idea of the compatibility of one brand to another, it's unwise to chance mixing two that don't like each other.
And even if they are compatible, mixing them deletes the long-life corrosion protection, dumbing protection down to the default 2-years.
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Further: Coolant is not like brake fluid or motor oil, where all of them within a given grade are compatible with each other.
--
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On 03/18/2012 06:41 AM, Tegger wrote:

oh, puh-leeze.
<http://www.eetcorp.com/antifreeze/antifreeze-faq.htm
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On 3/18/2012 6:41 AM, Tegger wrote:

OK, but in most cases when I want to top off the coolant to replenish the loss over time, I have no idea what coolant the shop was using when they filled the system last time. So mixing different brands here is likely. Heck, last time, as I found out, my well regarded independent mechanic specializing in Japanese cars, used tap water to mix the concentrated coolant. When I asked him about that, he dismissed my concern by saying that the tapwater here was pretty soft and he never heard that using tapwater for mixing could be a problem. (Funny, even I've known about that!) But then, maybe that tapwater is the reason why I've just noticed the early signs of coolant vapor condensing inside my windshield after only a few years of heater core replacement. Shoot, that will be another expensive repair job. Perhaps it is time to look for another shop for that job or going back to the Honda dealer again. I better get some bids on that job first because it might cost me more than what I could fetch for the whole '94 Accord.
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On 03/18/2012 10:45 AM, cameo wrote:

indeed.
as do most shops. apart from anything else, it's cheapest. for the shop anyway, not the customer.

like most shops have never "heard" of bad head gasket repair practices being the inevitable death of that engine. it's not because the problems don't accrue to their bad practice, it's because /that/ particular shop costs the customer money so the customer takes their business elsewhere - them become someone else's problem.

q.e.d.
unfortunately, you can't rely on a dealer to not use tap water. most of them take the view, and you have to be sympathetic to this, that the customer is going to use it, so it's not going to make any difference, it's only the super-anal independent and large fleets that use the same equipment for many years, that bother.

i never understood the logic of this thinking. buying a new car costs money down, money lost through depreciation, more expensive insurance, and [for most people] monthly payments - that all amounts to many thousands of dollars a year. how can that possibly be "cheaper" than repairing what is now essentially a "free" car? sure, go ahead and replace a car one doesn't like, or that one feels has has social implications, but replacing it because its current value is supposed to be weighed against repair cost when the replacement ends up being even more expensive??? i don't get it.
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On 3/18/2012 11:10 AM, jim beam wrote:

So what is one to do then if he is not a super-anal independent?

I understand you here and up to now this was pretty much my own thinking as well. That's why I kept the car this long. Even though the engine and transmission, along with other major components still function almost as well as in the firts year but the increasing frequency of repair jobs of auxiliary componenents is starting to nickle-and-dime me to death. Because of them, I would not even risk a longer trip with the car. But eventually I just might bite the bullet and pay for a heater core replacement again. In the end though I'll still have an old car on which something else might go wrong again when I least expect it. It would not be too much of a problem on a local trip but could ruin my whole day on a longer one, especially at night somewhere.
There is a school of thought that once the maintenance bills add up to a certain value of a car, it's better to get a new one than repair the old one. Isn't that the basis of how the insurance companies decide when to total a car and when to pay for the repairs?
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On 03/18/2012 07:43 PM, cameo wrote:

i just assume it's diluted with tap water and just drain the system and refill with what i /know/ to be properly constituted. but that's /me/ being anal, and also inclined to get under the hood anyway. there's no reason you can't show up at an independent with a couple of containers of antifreeze you did yourself and ask them to drain/refill for you.

that has to be one of the most severely p.i.t.a. jobs possible on a honda. literally everything around it has to come out. i sympathize. and i'd look into other leak remedies first.

if you've followed a program of preventive maintenance, that "if" gets pretty much eliminated. i've spent quite a bit on my 89 civic in the last few years. driveshafts, alternator, starter, battery, brakes & disks, radiator, hoses, exhaust, catalytic converter, oxygen sensor, suspension bushings, etc. not necessarily because the old stuff wouldn't have lasted longer, but because i wanted to*. and each should be good for another 10-20 years. and all of this expense together is considerably less than what my previous new car cost me in depreciation over the same time frame.

where does that "school of thought" come from? i put it to you that it's the same people that never do the math on the /real/ cost of ownership!
* and this is where "wanting to" comes in. i figured that if i compared real costs of ownership, i could /afford/ to plow quite a lot of money back into the 89 and still be ahead. so i did. and can afford to keep on doing so.
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On 3/18/2012 8:45 PM, jim beam wrote:

I already decided that I'll just do that in the future. Just like I've been doing it with oil. I have a feeling he already looks at me as if I was some kind of "super-anal" smart ass with my insistence of using my own Castrol oil, so he would be even more reinforced in that view if I insisted in my own antifreeze as well. I imagine mechanics don't really care for customers who try to act as if they knew more about cars than they do and might suggest to do the work myself if I know so much. It's understandable, no?

I know and that's why I am not surprised by the high bill for it. Frankly, I wonder if the current heater core that was installed a few years ago was a high quality remanufactered unit in the first place or perhaps it was damaged during installation. That could also be the cause, not just improper coolant, right? If I decide to go with replacing the core again, I am seriously thinking whether it wouldn't be a good idea to get a new core from one of the online Honda dealers, like Majestic, that has good prices on OEM parts.
In any case, what other remedies were you thinking of?

It might, but in the last few years some of the hoses found a way to fail even though I've been always sticking to the manufacturer recommended preventive maint. schedule.

Oh come now, you've must have heard that too before!

Preaching to the converted here. I'm just saying ...
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On 03/19/2012 11:02 AM, cameo wrote:

most techs, regardless of whatever it is, aren't usually high up the ladder in the "people skills" dept, so you'll have to forgive them if they roll their eyes. and frankly, the average customer /doesn't/ know more then they do, so a combination of people skills and customer knowledge is something /you/ are going to have to present artfully.

absolutely. one of the reasons most manufacturers now use aluminum matrix heat exchangers is that old fashioned solders can be dissolved by modern long life anti-freeze. most remanufactured items are still soldered, so absolutely, this could have been the problem.

i would. this item is /such/ a pita, and the expense is such a small fraction of overall labor, it's not worth /not/ getting one that's going to last as long as possible.

sodium silicate solution, aka "blue devil head gasket sealant" or whatever it's called.

that's unfortunate. honda hoses, the made in japan variety anyway, usually last a ridiculously long time.
now, thinking about this, one thing that can negatively impact hose rubber is sodium hydroxide solution. and two possible sources of that are radiator flush chemical, and dexcool antifreeze. and that could impact your heater core too. have either been used do you know?

all i've heard is the constant drip-drip-drip of the media trying to instill "it's not worth repairing" thinking into the sheeple. that and the generally pitiful state of current math education.

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On 3/19/2012 8:37 PM, jim beam wrote:

Hm ... Does that mean that most manufacturers now use aluminum matrix heat exchangers for recent models only or also do as OEM replacements for older models?

I think that's what I'll do. I've already checked for online prices for a new OEM heater core for my Accord is around $300 ay Majestic and BK Honda which the dealers sell for over $600. Figures, huh? I wonder what the dealer's cost is because I'm sure even those online dealers make some money on the $300 price. Of course, I'm sure my mechanic will probably say that he can get a remanufactured one for something like $180 but to me that difference is miniscure compared to the whole replacement bill that might be repeated again in a few years.

But I thought those solutions may make things worse in the long run.

I wish I knew what was used. Most shops don't tell such things to the customers. By the way, the original hoses did indeed last a long time. But not just hoses could suddenly fail in such an old car, but suspension items, boots, bushings, etc. Then I once detailed my adventure with alternator brush replacement, too. These kind of things happen in increasing frequency on old models even if I keep to the manufacturer's maint. schedule. Fortunately they tend to be not the most expensive things to repair but could really ruin your day if they happen on a long trip. Fortunately I seldom make such trips these days.
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On 03/20/2012 10:57 AM, cameo wrote:

i think most oem replacements are the same as originally fitted. basically, they put a bunch into storage when they stop production, and that's pretty much it.

aftermarket is $98 at napa. but i'd still go with oem if it were my car.

it's relatively inert chemically, it just crusts everything up where it gets a chance to leak. which is why it stops things leaking. is it a proper cure? no. but will it stop a leak for a year or two? sure it will. depends how long you want to keep the car.

but most of this stuff isn't in the maintenance schedule. that's why you need to inspect and replace when necessary. it's what they do with a lot of aircraft maintenance.

in the grand scheme of things, brakes, alternators, belts, batteries, etc. aren't very expensive. if you have the time and inclination, you can sign up for your local community college car maintenance classes. you may not end up wanting to do the work yourself, but at least you'll know more about what you're looking at and be able to stay on top of a regular inspection schedule. it'll save you a ton of money in the long run. like a friend of mine getting dinged $500 for a radiator hose when he was on a road trip. $500 to change a hose that could have been inspected and changed ahead of time, and which would otherwise cost $25.
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On 3/20/2012 8:02 PM, jim beam wrote:

So then I would probably not get aluminum matrix withe OEM replacement.

Wow, it's even cheaper than I thought. But the savings would still mean nothing if I had to redo this core exchange in a few years. I might go with that for the radiator because it's not as labor intensive to replace.

OK, so that's what I thought, too.

Well, my guy does inspect things, too, but I doubt he is very thorough with it.

Sorry, Jim; I'm now too old for going back to college and my back is also not what it used to be. But I think your proposition is a good one for younger guys. In fact, in my younger years when I had an'84 Corolla SR5 coupe, I installed the whole A/C system myself from a factory kit because the dealer could not get me the new car with built-in A/C and otherwise I really liked the car. After installation, when I had to drive the car to the dealer for charging the the system, the mechanic wouldn't believe I did the installation myself. He said he could not have done it better himself. ;-) It was still a RW drive model and maintaining it was easy. I really liked that little coupe.
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On 03/20/2012 09:13 PM, cameo wrote:

yup, that's what i do. some aftermarket radiators are pretty cheap and nasty, but they'll usually last 5 years. by which point, all the stones, bugs and other debris that messes them up can be expunged for a fraction of the cost of the oem - which cost dictates you'll struggle on with for as long as possible and their sudden failure becomes a real problem.

usually, they're "too thorough" with the stuff that's easy to fix and ignore the harder stuff. a friend of mine got dinged $450 for a motor mount that was allegedly "cracked". but it was one of the ones where it has a thin rubber web that basically is just to hold the guts in position until it's fitted, then is irrelevant. it takes about 10 minutes to replace - should it actually be necessary - and costs <$60 in parts. all this from a honda dealer that also uses aftermarket belts but charges you full oem honda pricing too!

well done!

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On 3/21/2012 8:13 AM, jim beam wrote:

A good chunk of the credit should go to Toyota because that factory A/C kit came with such detailed and illustrated step-by-step instructions that they was similar in quality to Heathkit instructions of the time. And I used to be kit builder.
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Possible. And not a great practice.
What's also possible is that the shop went by color and topped up with the same color that was already in there. That's what my guy does.

Then he's not using Honda coolant, which is a premix...

If /correct/ coolant is used, and is changed at the /correct/ intervals, the heater core will outlast the vehicle.
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On 3/19/2012 4:56 AM, Tegger wrote:

I think you just don't know when mechanics will use short-cuts instead of good practices.

Except -- according that antifreeze FAQ: "In the past, most antifreezes were green. Now, manufacturers use a variety of colors in their antifreeze product lines. Green generally, but not necessarily, indicates an automotive or light duty formulation. Orange antifreeze generally means extended-life type of antifreeze. It is ethylene glycol-based like most green antifreezes but contains different corrosion inhibitors. The various manufacturers use colors to identify their products in a bit of marketing gamesmanship; however, there are no hard rules governing the use of these colors. "
So much for relying on colors.

Indeed he is not. He also does not use the Castrol oil that my Honda dealer uses. That's why I also bought the oil before I took the car for oil change. I wish I had done the same thing with coolant.

Unfortunately this lesson comes a bit too late for me. :-(
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Then maybe there's more to it than color. I just watched him, I never asked him about it.
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Just to change the subject slightly, you mentioned the Honda Coolant is a pre-mix...Do you know to what temp that protects your cooling system from freezing? DaveD
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Let me have a look at the bottle...
It says it's a 50/50 mix. Freezing point: -35F Boiling point: 268F
There's a little asterisk that tells you that the boiling point is calculated at sea-level, and with a 16-lb cap. I'm about 800ft above sea level, and my car takes a 13-lb cap. I don't know what that does to the boiling point.
Also the label says not to drink it. I guess that's important.
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