Penrite Radiator Flush will help easily remove sludge, scale and rust from your cooling system; enhancing performance and extending component life. The non-acidic formula is safe to use in all cooling systems and wont damage any metals, plastics or rubbers. Penrite radiator flush is very simple to use and requires as little as 7 minutes to completely clean cooling systems. Ideal for use when changing coolant, replacing a radiator or for cleaning blocked cooling system components to help increase cooling performance. 1 bottle will treat most standard passenger cars and small commercials, for larger cooling systems use 1 bottle for every 15L of coolant.