For the radiator to remain in perfect working order over a long time, the overriding requirement is that the system remains absolutely leakproof. Special attention is paid to the connectors between the many individual parts, such as radiator tanks, radiator pipes, radiator covers, inlet and outlet. RTV-1 silicone rubbers have proven to be ideal for leakproof sealing of radiators straight after manufacture. Both the air-side and part of the water-side coating of the cooler floors are sprayed with RTV-1 silicones.

Silicone elastomers also make effective screen-printing and coating materials. In these cases, for example, soft-seals are treated with an impregnating agent to reduce their pore volume. Highly stressed surfaces are then screen printed with silicone rubber and the whole seal is coated with a topcoat.