Moroso Radiator Leak Sealant

Moroso Radiator Leak Sealant: Race-Proven Cooling System Protection

Moroso Performance Products has been a trusted name in performance and racing since 1968, and that same engineering philosophy extends to their radiator leak sealant lineup. While Moroso is widely celebrated for oil pans, ignition components, and chassis equipment, their cooling system sealants reflect an equally rigorous, race-derived approach to keeping engines alive under the most punishing conditions.

Two Distinct Formulas for Every Cooling System

Moroso addresses radiator and cooling system leaks with two targeted products, each engineered for a specific environment:

• Ceramic Engine Seal (Part #35500): This sealant is Moroso's flagship cooling system formula. It is designed for use in a clean, antifreeze-free system, and it works equally well in both aluminum and cast-iron blocks and heads. The ceramic-based chemistry coats and seals the entire cooling system — stopping radiator leaks and addressing minor cracks in the engine block or cylinder head. As the brand puts it, if this won't seal it, you'll have to weld it.
• All Weather Seal (Part #35520): Purpose-built for mixed-coolant systems, this formula is specially designed to stop cooling system leaks even when antifreeze is present — making it ideal for daily drivers and vehicles operating in sub-freezing climates. It targets radiator leaks and cracked blocks without requiring you to drain and flush the system of antifreeze first.

Why Moroso's Approach Stands Out

Most radiator sealants on the market are generalist products. Moroso, by contrast, develops its cooling system chemistry with the same mindset that goes into every product they manufacture: designed and tested by racers, for racers. The Ceramic Engine Seal has a documented history of use in oval track and drag racing applications, where an unexpected coolant leak can end a race — or an engine. For best results, Moroso recommends thoroughly cleaning and flushing the cooling system before application, ensuring the sealant can bond fully to any leak points.

The compatibility of the Ceramic Engine Seal with both aluminum and cast-iron engine architecture is particularly noteworthy. Many older and performance vehicles use a mix of materials across the block, heads, and radiator — and a sealant that works across all of them eliminates guesswork. The All Weather Seal fills the complementary role for modern vehicles that run year-round antifreeze mixtures.

Moroso's Legacy in Performance Chemistry

Moroso Performance Products, founded by Dick Moroso in 1968, has grown into one of the world's most respected suppliers of automotive performance and racing equipment, with a catalog spanning thousands of products across oiling systems, ignition, fuel, chassis, and more. Their chemical and sealant products carry the same race-heritage credibility as their hardware. Explore the full range of radiator leak sealants to find the right Moroso formula for your cooling system needs.