Original !! CT1 Miracle Seal 250ml, Heating Leak Sealer, radiator - Leaking seal. CT1 Miracle Seal 250ml Permanently seals small leaks anywhere in the cooling system. Seals leaks in radiators, hose pipes and water pumps. Can even SEAL HAIRLINE CRACKS IN ENGINE BLOCK. Guaranteed; Will NOT clog the system thanks to a revolutionary new formula. Is compatible with all types of water based coolants. Is not affected by Anti-Freeze and will continue to seal the leak. Voted no1 In the market place.