ok, to say that we have more problems with the cooling system now, vs. then, is just hearsay, or skewed perception, imho. back in the 80's all those cars had plenty of problems. water pumps, cores, hoses,etc were commonplace repairs. communication was nil to most, and all the cores were much more stout, providing longer life during abusive/neglected conditions.....but they would still rot away at the same rate, none-the-less. now, as for it being the 96-98, well it's not confined to that either......go all the way back to 91, where the plastic gaskets were introduced...same exact problem (other than sludge) expired coolant eats them, period. these are the isuzu-gm collaborated motors. before then, was more gm, and 99-00 phased to 100% isuzu engines....plain and simple manufacturing, not just coolant problems. you know, i kinda laughed at that aluminum comment.......yes, dex-cool responds to oxygen, that's not news, but it doesn't eat the aluminum until it has been run out of life.......so will conventional. you see, aluminum also responds to oxygen. raw aluminum exposed to air will rapidly oxidize, though you can't visually see it until it builds up. what you are seeing is the coolant washing the oxidation away, much like water-wetter, and bonding with the surface for better heat transfer.