--- product_id: 258773006 title: "9966 Radiator Leak Stop 325ml, Cooling System Sealant Additive, Coolant Leak Sealer for Radiators, Heater Core, Water Pump, Gaskets, Clamps & Small Cracks, Treats up to 12L" brand: "mannol" price: "Β₯1946" currency: JPY in_stock: true category: "Mannol" url: https://www.desertcart.jp/products/258773006-9966-radiator-leak-stop-325ml-cooling-system-sealant-additive-coolant store_origin: JP region: Japan --- # Compatible with coolant & water Treats up to 12L cooling systems Seals micro leaks fast 9966 Radiator Leak Stop 325ml, Cooling System Sealant Additive, Coolant Leak Sealer for Radiators, Heater Core, Water Pump, Gaskets, Clamps & Small Cracks, Treats up to 12L **Brand:** mannol **Price:** Β₯1946 **Availability:** βœ… In Stock ## Summary > πŸ’§ Stop leaks, save drives β€” keep your engine cool and your peace of mind cooler! ## Quick Answers - **What is this?** 9966 Radiator Leak Stop 325ml, Cooling System Sealant Additive, Coolant Leak Sealer for Radiators, Heater Core, Water Pump, Gaskets, Clamps & Small Cracks, Treats up to 12L by mannol - **How much does it cost?** Β₯1946 with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.jp](https://www.desertcart.jp/products/258773006-9966-radiator-leak-stop-325ml-cooling-system-sealant-additive-coolant) ## Best For - mannol enthusiasts ## Why This Product - Trusted mannol brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - β€’ **Compact Power Dose:** 325ml bottle treats up to 12 litresβ€”perfect for most vehicle cooling systems - β€’ **Leak-Proof Confidence:** Seals small radiator, gasket & pump leaks before they escalate - β€’ **Multi-Material Mastery:** Safe for aluminium, copper, plastic & composite radiators - β€’ **Quick Fix or Early Warning:** Temporary sealant that buys time before professional repairs are needed - β€’ **Universal Coolant Compatibility:** Works seamlessly with any coolant or plain water for versatile use ## Overview MANNOL 9966 Radiator Leak Stop is a 325ml cooling system additive designed to seal small leaks in radiators, heater cores, water pumps, gaskets, clamps, and minor cracks. Compatible with all coolant types and water, it treats systems up to 12 litres and supports aluminium, copper, plastic, and composite radiators. Ideal for temporary or preventive leak management, it helps maintain engine cooling efficiency and prevents costly breakdowns. ## Description MANNOL 9966 Radiator Leak Stop 325ml is a cooling system sealant additive for liquid-cooled internal combustion engines and interior heating systems. It is designed to help seal small leaks in the cooling system, including leaks around gaskets, clamps, small radiator cracks, water pumps, cylinder head gasket areas and cylinder block areas where this type of additive is suitable. The formula is made with metal polymers and special fibres and is compatible with coolant or water. Mannol states it is suitable for radiators made from aluminium, copper, plastic, composite and other common materials. One 325ml bottle treats cooling systems up to 12 litres. ## Features - RADIATOR LEAK STOP ADDITIVE – MANNOL 9966 is a cooling system sealant additive designed to help seal small leaks in radiators, heater systems and liquid-cooled engine cooling systems. - HELPS SEAL SMALL LEAKS – Suitable for leaks through gaskets, clamps, small radiator cracks, cylinder head gaskets, water pumps and cylinder block areas where a sealant additive is appropriate. - COMPATIBLE WITH COOLANT OR WATER – Mannol states the formula is compatible with any coolant as well as water and suitable for liquid-cooled engines with aluminium, copper, plastic or composite radiators. - 325ML TREATS UP TO 12L SYSTEMS – One 325ml bottle is sufficient for a cooling system up to 12 litres. Add to the expansion tank or radiator according to the product instructions. - TEMPORARY OR PREVENTIVE SUPPORT – Useful for micro leaks and hard-to-find coolant loss. If leaks are not eliminated within 3 days, Mannol advises that mechanical repair is required. ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B0050CIV5O | | Best Sellers Rank | #12,786 in Automotive ( See Top 100 in Automotive ) #99 in Oil & Fluid Additives | | Brand | MANNOL | | Customer Reviews | 3.8 3.8 out of 5 stars (92) | | Date First Available | 8 January 2015 | | Item Weight | 300 g | | Item model number | 9966 | | Manufacturer | MANNOL | | Manufacturer Part Number | 9966 | | Product Dimensions | 30.5 x 23.5 x 12 cm; 300 g | | Voltage | 12 Volts | ## Images ![9966 Radiator Leak Stop 325ml, Cooling System Sealant Additive, Coolant Leak Sealer for Radiators, Heater Core, Water Pump, Gaskets, Clamps & Small Cracks, Treats up to 12L - Image 1](https://m.media-amazon.com/images/I/611BcP-ZCYL.jpg) ## Frequently Bought Together - MANNOL 9966 Germany Radiator Leak Stop, 325ml - Turbo Radiator Coolant Green 1Gln - Mannol HTE - Germany (9965 2 Pc Pack Radiator Flush Cleaner) --- ## Why Shop on Desertcart? - πŸ›’ **Trusted by 1.3+ Million Shoppers** β€” Serving international shoppers since 2016 - 🌍 **Shop Globally** β€” Access 737+ million products across 21 categories - πŸ’° **No Hidden Fees** β€” All customs, duties, and taxes included in the price - πŸ”„ **15-Day Free Returns** β€” Hassle-free returns (30 days for PRO members) - πŸ”’ **Secure Payments** β€” Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** β€” Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.jp/products/258773006-9966-radiator-leak-stop-325ml-cooling-system-sealant-additive-coolant](https://www.desertcart.jp/products/258773006-9966-radiator-leak-stop-325ml-cooling-system-sealant-additive-coolant) --- *Product available on Desertcart Japan* *Store origin: JP* *Last updated: 2026-09-17*