I was working for Chevrolet when Dex-cool came out until 2000. We knew it was a bad idea when they introduced it and it only took 2 yeras before we knew for sure for the reasons being stated. BUT GM is lying, it wasn't because of the levels it was because Dex-cool turned into little black balls of sand like shit that plugged up the passages.
Another bad idea from them is one they are being sued over now. We knew it sucked when we first saw it was the self opening and closing sliding van doors. Turns out they don't latch right and are prone to opening when you drive down the road. Whoda thunk it? Well, we techs did as soon as we all saw the first one work right after it rolled off the car carrier.