I had used Dex Cool in my 1983 Mustang w/5.0L engine for over one year. When I had this vehicle in for replacement of a thermostat my mechanic recommended that I not use Dex Cool in my engine due to it’s being an acid based formulation as opposed to Prestone being a alkyline based formulation. The Dex Cool, he claimed would cause damage to the aluminum components in my engine. When he replaced the “stat” he drained and flushed the cooling system and refilled it with Prestone anti-freeze.