i've had this antifreeze and distilled water mix with a piece of aluminum and copper submerged in it for like a month or something. It's been sitting in my garage all this time and i just rembered it, no corrosion yet. There was like 10 dead crickets in it so i guess they liked it
Anyways i guess antifreeze does protect against corrosion pretty well, the aluminum didn't have any weird coating on it either.