No. The reformulated Prestone green in the yellow jug and the ST (also green) extended life coolants are closer to DEX-COOL - at least insofar when comparing to Prestone's own orange dyed fully GM approved DEX-COOL compatible brew. (All have the same corrosion inhibitor per the listings on the back of the jugs.). Havoline/Mr. Goodwrench DEX-COOL use the hydrated potassium salt of 2-EHA, Prestone,
et al use the hydrated sodium salt of 2-EHA and another salt,
sodium neodecanoate. (I'm unsure whether this extra corrosion inhibitor hydrated salt provides a performance advantage or merely a convenient dodge around ChevronTexacos's patents... or none of the above...) This "extended DEX-COOL family" is related insofar as they all use "OAT" corrosion inhibitors, no phosphates, no borates, no amines, no nitrites, and no SILICATES.
G-05 employs
reduced levels of silicates and a different hydrated organic acid salt,
sodium benzoate, as its "OAT" corrosion inhibitor. The combination renders G-05 a hybrid ("HOAT") G-05 also is free of amines, borates, nitrites, and phosphates in deference to Europe's generally abysmally hard water. (Like Europeans can't be bothered with distilled or de-ionized water when they service their cars' cooling systems every three or four years?
)
The Japanese (Toyota, Honda, and Nissan) are more in line with the DEX-COOL philosophy with "OAT" corrosion inhibitors and no silicates. But, they
do contain phosphates which provide a quick protective bond with aluminum. (It can take a while for organic acid salts to bond to aluminum. Also, if something damages the organic acid salt bond, phosphates can provide a bandage effect until the organic acid "skin" is re-established.) Co-reliance on inorgainic phosphates
may lead to the interpretation that the Japanese coolants are a "HOAT" coolant. More a syntactical distinction without a real difference so far as I'm concerned. (But, what do I know?..)
The Japanese and GM feel silicates gelling and then falling out of solution as hard precipitates are implicated in premature water pump seal wear. The Europeans feel that issue isn't a problem so long as the silicates level is reduced from the conventional coolant levels of the past.
[ October 25, 2004, 09:41 PM: Message edited by: Ray H ]