Is there a substance in Dex-Cool that crystalizes after the proper puddle has evaporated? Because there are just such white crystals on the garage floor under my car. If that is not leftover salt from the winter, then maybe there's a clue to the coolant leak that has plagued me for months.

 

Even Prestone can crystalize too. The additives in coolents will at times leave a mark.

Winter salt will last if you have not swept or wash the floor. It never goes away on it's own.

 

Yes. Dex Cool will crystalize. You should see what that crap looks like when it solidifies in the engine.