Can I use Fernox Protector F1 or Filter Fluid+ Protector in old systems?

Fernox Protectors are suitable for use on systems of all ages. However, it would be  advantageous to clean and flush the system with Fernox Cleaner F3 to remove  sludge before adding the Protector F1.

Alternatively, the universal Fernox Filter Fluid+ Protector can deliver sludge and debris to an existing in-line filter or a newly installed TF1 Filter, whilst protecting the system against further corrosion formation.