I can attest to the poor characteristics of dex-cool. I worked in a g.m.dealer for some time. we had cars coming in with 60,000 miles on them and the coolant was grease! I used to get so peeved when I could'nt get the writers to sell the customer a coolant flush. I argued it's better to admit that the coolant does'nt last 100,000 miles, and get it flushed out. than to let it develop into engine damage later. They never listened.......