drifter420, if you check the ingredients on the reformulated standard Prestone (and ST, too) against those of Prestone's own fully licensed and GM Approved DEX-COOL, they're all exactly the same. These fluids differ from the commonly reviled (unjustly in my opinion) Havoline/Mr. Goodwrench DEX-COOL fluid slightly in the corrosion inhibitor makeup. Whether this slight difference results in any performance difference over the Havoline/Mr. Goodwrench fluids is unknown. (they're all "OAT" fluids, and use at least one common organic acid radical) The only differences, though, between the standard Prestone and ST fluids and Prestone's DEX-COOL are the dye color (flourescent green for standard Prestone and ST, orange for Prestone's DEX-COOL) and the licensing fee Prestone paid GM to use the "DEX-COOL" copyrighted trademark. As to the rumor that mixing DEX-COOL with older (and largely unavailable, now) silicate-based conventional green fluids causes dire chemistry incompatibilities, all I can say is that Havoline's own remarks indicate that mixing DEX-COOL with conventional "green" merely results in the loss of DEX-COOL's extended life properties to the shorter 2-year working life of the conventional fluid. Prestone and ST give the same advice for their new extended life reformulated fluids, too, as well as the Prestone DEX-COOL fluid. For myself, I've had excellent long-term service with Havoline DEX-COOL in a '96 Accord and the factory-fill DEX-COOL in a '00 Cavalier, though I just flushed and refilled with ST extended life in my '03 Sonata. I'm of the opinion that the majority of drivers put cooling system maintenance in the same class as taking out the garbage - something they'd rather not deal with, even to merely routinely checking the fluid level in the radiator (NOT the overflow bottle!). Compounded by the all-too-frequent assumption that "extended life" means they don't even have to check the cooling system's level for five years, these owners find it easier to blame the brand of coolant instead of their own indifference when the inevitable cooling system troubles arise. (Apparently this type of psyche is oblivious to the common sense metaphor, "Trust in the Lord, but keep your powder dry.") Certain GM engines are known to have gasket and radiator cap problems, too - even to the extent that GM has repaired them out of warranty when the owners were persistant. But, presuming you're an enlightened BITOG memeber without one of the suspect vehicles and who stays on top of things, then, if you're still really nervous about DEX-COOL, just go with a "HOAT" G-05 fluid so you can sleep at night.
[ October 13, 2004, 11:54 AM: Message edited by: Ray H ]
