More relevant/interesting stuff here, from the one of the forums at
www.bobisthoilguy.com - see
http://www.bobistheoilguy.com/forums/ub ... er=1467026. Note the bottom line! If nothing else, it explains why we can't get an aftermarket coolant specified to be compatible with our Nissan's OEM stuff. Am now trying to work out whether my 3-years long life Glysantin based Comma G48 HOAT, which caused no Bongo V6 problems from late 2008 until now, has been quietly munching at my silicone main hoses, since they were fitted in August!!
"Coolant technology has independently evolved in Japan, North America, and Europe. The engineers who created these technologies studied and cited each other's patents but developed their respective approaches based more on practical experience than on theoretical models.
For the past few decades, nearly all automobile engines manufactured in Japan have been made primarily of aluminum. In North America, most engines are still made from cast iron, although aluminum is rapidly gaining market share. In Europe, aluminum has been dominant for decades but not as dominant as in Japan. (For example, the ubiquitous VW/Audi 2.0T engine has a cast iron block.)
Aluminum and iron have very different corrosion properties and require different antifreeze formulations for optimal performance. In particular, aluminum fares best with a "low pH coolant" with a pH is in the range 7.8-8.3 while cast iron fares best with a coolant pH in the vicinity of 10.5. The Japanese quietly started using a form of HOAT (hybrid organic additive technology) in automotive applications over 15 years ago. (A HOAT coolant uses a combination of inorganic and organic additives.) They never relied on silicates because their coolant technology was specifically developed for aluminum engines. In this context, silicates were unnecessary and undesirable because of their abrasiveness (which attacks water pump seals). Japanese engineers also avoided borates (a form of inorganic additive) because they are abrasive and less effective than phosphates.
In North America, coolant technology evolved primarily to support cast iron engine technology but it also needed to accommodate some aluminum engine parts including the occasional use of aluminum blocks which first appeared in the early 1960s. (Buick introduced an aluminum V8 in 1961 but ceased producing it in 1963 and subsequently sold it to Rover. According to Wikipedia, one of the reasons GM dropped this engine was radiator clogging caused by coolants ill-suited to aluminum.) North American automotive engineers determined that they could accommodate aluminum engine components by adding silicates to their standard coolant originally developed for cast iron engines. The abrasiveness of the silicates was not much of an issue given the assumption that water pumps (and perhaps cooling system hoses) would be replaced at regular intervals.
In Europe, aluminum blocks have been widely used for decades, which has pushed coolant technology along a path much closer to the Japanese model than the North American one. European engineers also developed a form of HOAT technology (using benzoic acid as the organic acid) about 15 years ago but they used silicates and borates in the inorganic additive package. European automotive engineers reportedly had some negative experience with phosphates reacting with the tap water in some European locales. In addition, phosphates acquired negative environmental associations, so the European automotive industry developed and promoted phosphate-free coolant technology. As a result, European coolants have historically used borates (which are abrasive) in preference to phosphates.
North American automotive engineers apparently recognized that Japanese HOAT coolants were superior in aluminum engines to North American coolants. In the mid 1990s, chemical engineers at Texaco developed a new purely organic acid technology (OAT) called Dex-Cool with a low pH (presumably targeting aluminum) and a much longer life than than conventional North American coolant (and somewhat longer than the Japanese and European HOAT coolants of the era). Unfortunately, the formulation of Dex-Cool was based primariiy on laboratory experiments rather than practical experience; hence, it not surprising that Dex-Cool encountered major problems in real world usage after GM adopted it in 1996. It would be fascinating to hear the inside story of how and why GM embraced Dex-Cool technology.
Japanese automotive engineers strongly opposed the use of 2-EH (ethyl hexanoic) acid, the primary additive in Dex-Cool, because it attacks some compounds used in many engine gaskets. But Japanese engineers appreciated the long life of the Dex-Cool additive technology and revised their HOAT coolants about five years ago to rely primarily on a similar OAT package (based on organic acids other than 2-EH acid). The complementary inorganic additives in Japanese coolants, which reportedly provide more immediate corrosion protection than OAT, still include phosphates.
More recently, european automotive engineers have recently updated their HOAT coolants for longer life as well. In Europe, Glysantin has released longer-lived successors to their older HOAT coolants marketed as SOAT (Silicon enhanced Organic Acid Technology). Of course, their older coolants were silicon-enhanced (silicated) as well, but truth has never stood in the way of effective marketing.
The primary problem with Japanese coolant technology (in comparison with North American and European technologies) is that Japanese coolants are only marketed as OEM products. Essentially all Japanese automotive coolant is manufactured by the Japanese company CCI which has a North American subsidiary called Intac. But CCI/Intac does not produce any "aftermarket" coolant for North America. Although the Japanese manufacturers suggest that only coolants with their specific OEM labels are properly formulated for their vehicles, all Japanese automotive coolants appear to fall into two simple categories: "long life" (the original Japanese HOAT coolant) and "extra long life" (the revised Japanese HOAT coolant incorporating OAT without 2-EH acid). Within each category, the various brands of coolant appear to be nearly identical based on the limited information they have released (press releases and Material Safety Data Sheets (MSDSs). In fact, the MSDSs for some of the OEM branded coolants refer to the same CCI code numbers. Hence, if a cheap source of Honda/Toyota/Nissan/Mazda coolant in the proper category is available, it should work well as a substitute for any other brand of Japanese coolant in that category. In addition, according the Japanese manufacturers, "extra long life" coolant can generally be used to replace "long life" coolant, but the old coolant must be drained for "extra long life" service intervals to apply.
In Europe, BASF is the dominant coolant manufacturer under the brand name Glysantin. BASF makes a variety of different coolant formulations, most of which contain some silicates and none of which contain phosphates. Among these formulations, only Zerex G-05, a derivative of Glysantin G05 is readily available in the US aftermarket. Zerex G-05 actually appears closer in formulation to Glysantin G40 (the SOAT successor to Glysantin G05) than to its namesake because both G40 and Zerex G-05 have extended change intervals while G05 does not.
In North America, the owners of Japanese cars either have to buy OEM coolant (often at exhorbitant prices) or try to find an acceptable aftermarket match to Japanese coolant technology. Among the available aftermarket coolants, Peak Global Lifetime is perhaps the best match since it relies on OAT without 2-EH acid. But it apparently does not include a complementary inorganic additive package like the Japanese coolants. (If it did it would be called a HOAT coolant rather than an OAT coolant). Zerex G-05 is another credible option because it is a HOAT coolant that does not contain 2-EH acid but it incorporates silicates ("silicon enhancement").
My recommendation to the owners of Japanese vehicles is to grimace (at the price) and buy a Japanese OEM coolant."
These cars were built before OAT coolant was even dreamed about
The coolant was two years old and therefore ready for replacement. My local auto spares store, part of a national (UK) chain, was out of stock of the standard own-brand antifreeze but was fully stocked with their own-brand 'Advanced Coolant'. The information on the label quoted the usual compliance numbers, offered extended coolant life, better anti-corrosion protection and stated that the product was suitable for older engines. On that basis, following a cooling system flush, I decided to use the new coolant.
sorry just had a look for it and its been binned 
) some time back. They didn't seem to have a tech support dept as such, in the way a computer firm would, for example, but whoever it was proved very helpful - just wish I could remember what they were helpful about 
Until now, we've all been at risk of doing the wrong thing, one way or the other - I originally used "extended life" (3 years) green coolant, on advice from Wheelquick in good faith in 2008.
IF i decide to replace the coolant this year (not required really, i use carplan premium red long-life OAT coolant) Then i'll whip off the silicone hoses and check the inner bores for any degradation. Surely i'd have some visible evidence of coolant degradation (i.e silicone particles) if the silicone hoses had developed cancer of some kind? The coolant is still crystal clear. 