12 Oz. Radiator Stop Lea

The 12 Oz. Radiator Stop Leak from CYCLO is a vital coolant additive engineered to seal minor leaks in your vehicle's cooling system without requiring a complete radiator replacement or flush. As a mechanic, you know that small coolant seeps develop over time—corroded passages, hairline cracks in hoses, and weeping gasket joints are common culprits that plague aging engines. This product targets those gradual failures, buying you time and preserving system integrity until a full repair can be scheduled. It's ideal for drivers experiencing slow coolant loss, overheating tendencies, or budget constraints on immediate radiator work.

CYCLO's formulation works by conditioning and thickening the coolant film, helping the system self-seal micro-fractures and corrosion pits from the inside. The 12 fl. oz. concentrate is mixed directly into the radiator or coolant reservoir, dispersing throughout the entire cooling loop—block passages, heater core, radiator tubes, and gasket interfaces. Its chemistry is compatible with both traditional green and extended-life orange/pink coolants, though always verify your vehicle's coolant type before mixing. The lightweight, compact 1.02 lb package stores easily in any shop or garage, with a shelf life that makes it practical for preventive inventory.

Vehicle owners facing coolant seepage, older model enthusiasts running high-mileage engines, and fleet operators managing cooling system maintenance will find this additive invaluable for temporary stabilization. It performs best on passive leaks—weeping radiator seams, corroded freeze plugs, and minor hose cracks—rather than catastrophic failures. Installation is straightforward: drain or top off your coolant to near-full capacity, pour in the 12 oz. treatment, and run the engine until the thermostat cycles to distribute the additive throughout. For best results, allow 50–100 miles of normal driving before evaluating leak reduction; some seals may take several heat cycles to fully condition.