Small leaks caused by stone impacts, porous soldering points and hairline cracks in the cooling simple are easy to localize (one notices that the cooling water level is sinking).
eBay
2 x Prestone Radiator Stop Leak Triple Seal Protection with Kevlar 16.5 Oz.
eBay
For preventive use. It's not easy to find small leaks caused by stone chipping, porous soldered connections or hairline cracks in the cooling system. Usually the only clue is in the reduced coolant.
eBay
Liqui Moly Diesel Particulate Filter Cleaner Purge Pro-Line 0.5 L 5171. - for preventive use. Dispersion for sealing leaks in coolant circuits in passenger cars, trucks and buses. Reliably seals hairline cracks and smaller leaks.
eBay
Leave the agent in the cooling system to protect against future leaks. K2 Stop Leak 18.5g ensures long-lasting protection and peace of mind. Turn off the engine and pour the sealant into the radiator or expansion tank.
eBay
Seal HD HGV Gasket Radiator Coolant Stop Leak Repair 472ml. K-Seal is specially formulated to permanently seal most cracks in the engine block and head. K-Seal HD permanent coolant leak repair for HGV, heavy plant, agricultural and all large water cooled engines.
eBay
Holts Radweld is suitable for all cars & all anti-freeze, and is the Number One product for sealing leaks in your radiator system. Seals most leaks in the Radiator, Heater Core and Hoses. Holts Radweld not only seals but also protects containing rust inhibitors to stop rust forming.
eBay
Radiator Stop Leak Plus. no negative side effects on the water pump or heating circuit. Dispersion for sealing leaks in water cooling systems in motor vehicles. The product reliably seals hairline cracks and small leaks.
eBay