Who knows what the "wrong" antifreeze is, anyway? It isn't like we get to talk to the folks that built the cars. This new 2008 Hyundai I have specs a coolant change at 60K, 30K thereafter. Does that mean the syrup at the factory is "better"? My 2005 Accent had snotty, settled out of solution silicate swimming around in there the day they delivered it (it was built in Nov. 2004, I took delivery Feb. 2006), so I changed it out to G-05 at around 1000 miles when the dealer wouldn't replace the coolant. They didn't care if I changed it, but THEY weren't going to. G-05 should be good, right? G-05 is a nice clear Hybrid OAT, with a dash of silicate, it was spoken of highly here, so I flushed it but good with distilled water and went 50/50 G-05. What happens? New waterpump at 44,000. Do I blame the coolant? Not necessarily. Maybe the car sat on the lot too many months, who knows, but it DID fail with G-05. On my 1992 Elantra, the water pump only got changed every second timing belt, never for failure. The 92 Elantra? Orange DexCool licensed clone from Prestone. But I changed it every 30K.
I called the dealer to ask what to use on the 2005, they told me not to use DexCool, use yellow Prestone, which IS Oat, no silicate, an unlicensed DexCool clone, just like their orange Dexcool, without the orange, of course. So even the dealer doesn't know. Hyundai America doesn't know. The dealer doesn't know what Hyundai put in at the factory in Korea, nor does Hyundai America. The owner's manual says to use a good-quality ethylene-glycol coolant. Period. You're on your own.
So we're at the crux of the matter. And I doubt Hyundai is unique in this, at least amongst the foreign manufacturers. Go on, try to find out precisely what coolant they put in at the factory, in a foreign-built Toyota, Honda or Nissan. I defy you to get the same answer twice. Where does that leave us? Right back at the door of sound maintenance practice. Change the stuff once a year, pick one coolant and stick with it. If your car goes two years and you're comfy with that, the same coolant for all that time, go with it.
But seriously you guys, show of hands here, WHO REALLY thought 10 years ago that going 5 years and 100,000 or 150,000 miles on the original coolant was a good idea? Anyone think 100,000 miles on a set of plugs is a good idea? Those intervals invite negligence. Furthermore, far better than 99.999% of the motoring public, the folks right here on these pages know dammed good and well there was no car that was going to survive the maintenance practices GM specified for those V-6s back then. That's no matter the plastic manifolds, the DexCool or the bad gaskets. Those specs weren't prudent, they didn't make sense, and the predictable results slathered on more bad rep to the GM lineup.
So stop with the Dex-hate. It's nonsensical. Look at it this way if you will: In the lubrication realm, much has changed, better fuel control,alloys, base oils, additives, all pointing toward longer drains. But other than silicate reduction, and OAT, not much has changed in ethylene-glycol coolant since the old shade-tree days and nothing in cooling system design and construction has changed for the better. In modern cooling system construction, we have aluminum blocks, not iron, we have thin, crummy, plastic-tanked radiators with thin-walled aluminum tubes, not radiators with beefy, soldered brass and copper side-tanks with thick-walled tubing. Heater cores are crummy now, too. Everything is considerably different, but we're to believe that we can go 100,000 or 150,000 miles on these cooling systems as delivered today? Sorry. I don't buy it. And to blame it on the COOLANT is preposterous. To me, that is as nonsensical as blaming Pennzoil for the sludge in the engine that didn't get the oil changed for 15,000 miles.
My humble opinion, your mileage may vary.