Prior to 1997 Toyota used a conventional green coolant.quote:
Originally posted by LarryL:
Just had a service writer tell me there were two different Toyota red coolants, one regular and one long life, red and pink. What's going on, here?
That is not quite correct. The phosphate content which all three major Japanese automakers specify is for added quick aluminum protection - especially important now that the Japanese "big three" are filling their engine bays with aluminum motors, as well as using aluminum heater cores and radiators. Phosphate latches onto aluminum almost immediately. It has no effect on the generation of cavitation bubbles. OAT can take up to 3,000 miles of operation to build up an adequate protection film (though once established is very long lasting unless mechanically disturbed). The circulating "unused" phosphate is available to quickly repair the OAT protection coating in the event something sloughs some of it off. GM specifically rejected using phosphate out of concern that if it precipitated out of solution as hard crystal, it could cause waterpump seal damage. The Japanese automakers considered that an acceptable risk, and time, so far, sugggests they're right.quote:
Originally posted by Mickey_M:
It [Toyota "red"] is silicate-free but contains some phosphate, which provides some protection to the water pump from cavitation damage.
Duh! Could it be that Honda (Nissan and Toyota, too) want to sell you their pricey, proprietary antifreezes only available through their respective stealerships? Curiously, the Saturn Vue is equipped with a Honda motor, yet GM fills these vehicles with DEX-COOL on the vehicle assembly line despite Honda's dire warnings - so far I haven't heard of any problems - cavitation or otherwise.quote:
Originally posted by Mickey_M:
While you may believe DexCool doesn't cause problems, Honda takes a hard line that it does.
I did seriously believe that played a role. What in the world the European camp wants silicates and the Japanese camp insists phosphates? Before I put the Prestone OAT "all makes all models" in my Corolla, I went as far as to check out the patents filed by Prestone (I found 3) and Valvoline-Zerex (I found 2) to see what they said regarding ingredients, corrosion, and cavitation. Here was my reasoning to feel comfortable with Prestone. Prestone and Valvoline are big name companies with serious research and technology in this field. If the original DexCool has any problem, that would only show up after a long-term use, you would think these company would have known it by now and correct/improve it in their mix. But I was still wondering why Phosphates and my continuing research lead me this link Green Stuff Considered - Coolants and Corrosion written by someone who is a Ph.D in chemical engineering and doesn't seem to be associated with the coolant manufacturers. (I kind of have the impression that those "good" words about G-05 were originated from some Valvoline guy and spreaded out.) The gist of it is different inhibitors protect different metals. Silicate is good at inhibiting aluminum corrosion but not phosphate (poorly is the word in the article). However, Silicate is not indefinitely stable in solution (I think people call it gel-out.) Phosphate is effective at preventing cavitation and a well known inhibitor for ferrous metal corrosion (I have no idea if such metal is in the car.) but has a propensity to precipitate in hard water. This article makes me wonder maybe there is a good reason of using phosphrate because of the car design after all. But again, maybe not. It all comes down to what I (or you) feel more comfortable - spending a few more for the pricey one to have a piece of mind or just trusting Prestone/Valvoline.quote:
Duh! Could it be that Honda (Nissan and Toyota, too) want to sell you their pricey, proprietary antifreezes only available through their respective stealerships?
Ray H:
... Could it be that Honda (Nissan and Toyota, too) want to sell you their pricey, proprietary antifreezes only available through their respective stealerships? ....
There's no doubt that manufacturers and dealers are in it for profits.
That wouldn't explain, for example, why Honda doesn't warn against G-05, conventional coolant, or anything but DexCool and its clones. Ditto FOMOCO.
I've seen enough data to convince me that something in their field tests convinced them there was a risk, enough off a risk that FOMOCO has a NO ORANGE tag on their coolant systems.
The Mazda stuff is not a DexCool clone. It is, however, orange.
The only problem I am aware of with phosphates is that with hard water it can lead to a nice rock hard white deposit.
The issue of Honda engines in GM cars is an interesting one. Honda was and remains opposed to the use of DexCool in those engines, and as I understand it has made it clear to GM that problems related to the use of GM coolant in the V-6s aren't covered by their warranty agreement.
Without access to GM's warranty records, I don't know what experience they're having. GM hasn't been known for dealing with problems promptly or facing issues squarely.
Motor Magazine has had a number of articles on these coolant issues over the years. If I get some time I'll thumb through old issues and see what I can find. Meanwhile I did locate this from the Mobile Air Conditioning Society:
http://www.macsw.org/pdf/200410MS.pdf
and this reprint of a Motor Magazine article that summarizes much of what they've published:
http://gates.com/downloads/download_common.cfm?file=MOTORCoolantFeature.pdf&folder=brochure
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Basically Zerex is recommending a DexCool clone.quote:
LarryL:
So the pink may be for Toyota all alum engines but my 4Runner V8 has a cast iron block and alum heads and pink coolant. But it looks like the replacement is Toyota pink or Zerex Extreme Life... correct?