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All inhibitors work by coating the metal.
The inhibitor in Green Stuff, silicate, can build up, they say, reducing heat transfer. Paradoxically, it loses effectiveness after a year or two. It's also said to be abrasive to water pump seals. Consider that silicon dioxide is better known as granite when it comes in big pieces, or sand when in small pieces.
Carboxylate, the inhibitor in Orange Stuff, remains effective for a very long time. At least 300,000 miles in big trucks (with another 300,000 after it's "recharged"), and at least 5 years/150,000 miles in cars. Or forever if it's in a Saab bottle (and I have a bridge for sale - or is it Saab confident that blown bypass valves will take care periodic coolant changes). Orange Stuff got a very bad rap on account of its tendency to create brown sludge (aka rust) when the cooling system of an iron engine allows oxygen in. That's not been an issue with Saabs, but has been with '90s GM cars and trucks that trace their cooling system design back to antiquity. It also has a tendency to erode water pumps that are so poorly designed that they cavitate. This is mainly a problem with Chrysler engines.
Blue Stuff and Yellow Stuff are a mixture of a sebacic acid based inhibitor with a sidgen of silicate added for good measure. It provides the best of both worlds: the silicate protects those nasty water pumps and the iron blocks when oxygen gets sucked in, while the sebacic acid based inhibitor gives long life. It also provides the worst of both, allowing for whatever seal erosion and heat exchange deposits silicate might offer.
I might mention that all the coolants are buffered to a pH of 11 or 12, so even though they may be described as "organic acid", they really aren't acidic. But remember that aluminum dissolves in sodium hydroxide (part of the buffering chemical), unlike iron. I think that might be where the organic acid foundation comes into play, becoming especially effective for aluminum.
Saab Brand Blue Stuff has traditionally contained a "bitterant", something that makes the otherwise sweet tasting glycol unappealing to animals and young children. Given the cost of coolant these days, there is absolutely no excuse for manufacturers not to spend the few pennies it costs to add a layer of safety to the product. Glycol destroys the kidney, resulting in slow painful death for animals and a painful, inconvenient, and expensively shorter life (on average) for people. I say "traditionally" because I haven't seen a bottle of Blue Stuff lately.
There's other product out there. Red Stuff is essentially Orange Stuff with nitrites added. This is for cars and trucks with "wet sleeve" cylinder liners. Remember the corrosion to water pumps when they cavitate? The high temperature of wet cylinder liners can cause "nucleate boiling", which is a lot like cavitation. The nitrites prevent this. It doesn't do anything, good or bad, in our engines with either iron blocks or aluminum blocks with dry cylinder liners.
Prestone is making a green product that combines carboxylate (as in Orange Stuff) with some silicate. The only thing it has going for it, IMO, is its ready availability in some neighborhoods. Every car parts store and department store with an automotive section seems to carry it. Where I live in Ohio, Orange Stuff and Green Stuff are always available, but Yellow Stuff seems to be around only in the fall, at least at AutoZone. So if you decided that you must use a "hybrid organic acid technology" coolant and didn't want to beat the bushes for either Yellow Stuff or Blue Stuff, at least it's there.
Finally, what do I use? I used to use plain green stuff, drain and fill each and every year, and never had cooling system problems. And in the 1970s and 1980s, I ran 60% to 70% coolant, figuring less water meant less corrosion. When the cars started coming with Orange Stuff, I just went ahead with the 5 year recommended cycle on the first change, and so far haven't had any cooling system problems. As older Saabs came and went since the introduction of Orange Stuff I have used Blue Stuff in them, with a two year change interval, but would just as easily use yellow stuff if I found it on the shelf when it was time for a change. Like I've said so often, the difference between blue and yellow is minimal, but the Blue Stuff has a bitterant added so I personally support its use. They make versions of all the coolants with bitterant, you just don't find them on the shelf.
I also used to flush it some, but with the advent of environmental issues and coolant being considered toxic waste, I've switched to just plain drain and fill, but will shorten the interval to 3 years. And with Global Warming I've scaled back to a 50% water mixture, for better heat transfer properties and reduced viscosity.
posted by 24.166.95...
, Fri, 8 Aug 2008 15:15:49, Sat, 9 Aug 2008 10:11:56, Fri, 8 Aug 2008 16:42:26, Fri, 8 Aug 2008 15:57:12
, Fri, 8 Aug 2008 19:21:37
, Fri, 8 Aug 2008 16:29:07
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