Regarding Dexcool itself, the serious issue with it was on GM 3.8L engines. A number of them had faulty radiator caps which allowed coolant to push into the coolant reservoir (good), but then sucked in air as the engine cooled. The reservoir remained full while the radiator got air into it. The oxygen in the air mixed with the coolant, oxidized both the ethylene glycol and buffers (needed to keep the coolant at a healthy high pH). The oxidized glycol and buffers became acids, and the acids ate away at aluminum parts inside the engine. On the 3.8L especially, the heat combined with acidity (often pH 3-4, which is quite acidic) ate away at the nylon intake manifold gaskets. Nylon is normally a great material for gaskets unless it is exposed to heat and acid. Coolant would run between the lower intake manifold and block, so when the lower intake gaskets failed, water would get sucked into the engine causing a catastrophic failure. While our trucks have nylon intake manifold gaskets, coolant does not run through them, except maybe to the throttle body. So, Dexcool never really caused many catastrophic failures on the 5.3 or 5.7L engines. If you are concerned, get some test strips to check for acidity each oil change. As for me, I've had to fix so many things (water pump, "T"s, thermostat gaskets), I've changed my coolant way too many times. Yeah, I could have reused it, but for the cost of coolant I decided to change it anyway.