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Good write-up about antifreeze Ever since I moved about 1/2 year ago I have been air cooling. My water cooling setup is not internal and consists of several "out of box" components like a 5 gal. plastic bucket for a reservoir and a cardboard box with the rad mounted on one side with a 120v 120mm fan mounted on the other. In other words it's a pain to get all set up. I was thinking about several alternatives to my system and have been playing with the idea of building a bong that uses a suspending material in the barrel as opposed to having to generate a spray. This is still on the drawing pad and will probably be what I go with. I'll document my adventure if and when I do it. Sooooo.... I'm looking around the net at cooling stuff and came across this comprehensive rundown on antifreeze and coolants. I thought it was informative enough to share. You will know just about all there is to know about coolants after reading this review. ---------------------------------------------------------- SOURCE Cooling System Info >> 'Jim Crider wrote'>> "Here's a response from someone who designs vehicle cooling systems for a living ...... (that would be me): Strictly looking at the heat transfer coefficient, straight water is the way to go. HOWEVER... straight water has its problems, notably a lack of certain additives that prevent cavitation of the water pump at high speeds, corrosion of the various metal bits present in all engine cooling systems, surfactants to lower the surface tension of the coolant (allowing it to "wet" the surfaces of the coolant passages better) and anti-foaming agents to keep the surfactants from making big bubbles. All these are present in antifreeze/coolant. The surfactants and anti-foaming agents are present in Redline Water Wetter. Water Wetter has limited to no benefit in a system using a commercial coolant -- it's simply adding more of something already present in sufficient quantity. Another drawback to straight water is that the freeze point and boiling points are closer together than a mix of coolant and water. A 50/50 mix of ethylene glycol and water will boil at 220F at atmospheric pressure at sea level, compare with 212F for straight water. A pressure cap, by the way, adds about 3 degrees F to the boiling point per psi above atmospheric pressure. And of course, water freezes at 32F, while a 50/50 EG/W mix will freeze at about -35F. This of course is useful should you live somewhere that gets cold (that would be most of the country this winter, it seems). There are two types of base coolant stock available right now: Ethylene glycol (EG) and propylene glycol (PG). Currently, no engine manufacturers selling product in the US recommend PG (sold by Arco as Sierra brand coolant), most caution against it (check your owner's guide). PG has a higher boiling point than EG (straight), but has a lower heat-transfer coefficient. EG coolants also come in several flavors, depending on the additive package (more below). BTW, PG isn't truly non-toxic. It's LESS toxic than EG, but PG coolant contains various and sundry additives that aren't really good for you. The LD50 (lethal dose in 50% of ingestion cases) for PG is about 4 times less than EG's LD50, but that's means we're talking along the lines of 16 ounces instead of 4 ounces for a small kid or large dog. And once it's been in a cooling system, it's picked up contaminants (metals, etc.) that aren't terribly good for you. Arco got in a fair bit of trouble and had to re-label Sierra (including all the stuff already on store shelves) a few years back when the FTC challenged their advertising claims and found them lacking in accuracy. Basically, the less-toxic claim only applies if you pour the stuff straight out of the bottle and onto the ground. Don't bother with it. And treat *any* used coolant as low-level hazmat. Small amounts can be disposed of in sanitary sewer systems, but you're better off making nice with the operator of the neighborhood quickie lube place, who will be able to take it off your hands and get it into the recycling stream, sometimes for a nominal fee. You're already talking to him about your used motor oil anyway, right? The green-dyed EG "conventional" coolant we all know and love has an additive package based around a silicate (and sometimes also phosphate) based anti-corrosion additive. It's well-established and does a good job. It can go 5 years/50K miles without worry. A few years ago, someone thought a long-life coolant (original plan: life of vehicle) would be a Good Thing. This lead to Organic Acid Technology coolant (OAT), which is marketed as "DexCool" by GM and has been factory-fill in their products (except C4 Corvette -- not sure about C5 Corvette) since 1995. It's the orange or orangy-red stuff. Someone along the line decided the word "acid" was a Bad Thing to try to sell, so OAT was recursively changed to Organic Additive Technology. It can go 5 years/100K or 150K miles -- provided it's not mixed with other coolant. OAT has less cavitation resistance than silicate-based coolant, and can attack certain sealing materials, so it's not a good idea to convert a green-coolant car over to OAT unless the manufacturer says it's okay. OAT also has a tendency to stain translucent plastics in things like overflow bottles and pressurized de-gas bottles with a funky brown crud. Oh, and OAT from one manufacturer isn't necessarily compatible with OAT from a different manufacturer. Texaco is GM's OEM supplier and is licensed to use GM's "DexCool" trademark on their aftermarket packaging. I'm not aware of any other company being licensed to do so. Many European automakers use a hybrid of OAT -- HOAT (Hybrid Organic Additive Technology -- clever, huh?), which is the OAT package with a small amount of silicates added to increase the cavitation resistance and make it less aggressive against those seals and gaskets. This is often pale yellow in color. DaimlerChrysler is using it in several car lines now, too, notably the LH sedans and the new minivans (It's possible the Sebring/Stratus twins now use it -- I don't have that handy at the present). This stuff seems to offer pretty much the best of both worlds -- it's not quite as long-lived as straight OAT, but it is much better behaved in operation than OAT, much like conventional coolant. Note that these three different additive packages are not really cross-compatible. No, they won't eat the insides of your radiator if you mix a little of one in with another in a pinch, but you'll be better to get the system flushed out and a fresh mix of 50/50 whatever your car needs put back into it. In my own cars, I run a 50/50 EG/W coolant mix. I happen to own cars that take conventional coolant, but if I owned a car that came with OAT or HOAT from the factory, I'd likely stay with it. The anti-corrosion additives, in particular, leave residues on the walls of the various coolant passages (that's how they work -- the residues coat the base metal and prevent corrosion), and it's tricky to convert an engine that's been run with one style of package to use another package and get the full benefit. Switching from conventional to OAT, for instance, requires a mild acid flush of the cooling system after removal of the conventional coolant and before pouring in the OAT if the long-life corrosion benefits of the OAT coolant is to be realized. Just pouring the OAT in after draining the conventional won't gain the full measure of added coolant life the OAT marketers (notably Texaco) like to use as selling points. Radiator caps are a whole topic unto themselves. Ask me about them another time -- my lunch hour is over and I gotta get back to work. ![]() Hope this is helpful. Jim Crider"
__________________ Then, as it was, then again it will be Though the course may change, rivers will always reach the sea. ---------------------------------------------- |
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