The Alde Glycol is a high-performance heat transfer fluid specifically designed for an aluminum heating system. It features superior corrosion protection however it is still recommended to replace the fluid every two years. Alde-branded glycol is recognizable by its blue-green color. It is recommended that you do not mix brands of glycol. If the glycol in your current system is a different brand or a color other than blue-green, we advise that you have the system flushed by a trained technician and refilled with Alde-branded glycol.