Permatex High-Temp Red RTV Silicone Gasket Maker, 11 oz — Heat-Resistant & Sensor-Safe Sealant

Permatex 81409 High-Temp Red RTV Silicone Gasket Maker is a heavy-duty, formed-in-place RTV silicone designed for engines and components exposed to extreme heat and harsh fluids.

Built for demanding automotive and industrial environments, this red RTV silicone creates durable gaskets that withstand wide temperature swings and fluid exposure. It bonds to metal and many modern component materials to replace or reinforce cut gaskets, coating pre-cut gaskets for added sealing reliability. The product’s intermittent temperature capability and oil resistance make it suitable for engine bays, transmission pans, and other high-heat areas where a flexible, long-lasting seal is required.

How well does this gasket maker handle high temperatures?

Permatex 81409 is formulated to tolerate intermittent exposure from -65°F up to 650°F, which covers many engine and exhaust-adjacent applications. Its silicone base maintains flexibility through thermal cycling to reduce cracking and shrinkage.

• Intermittent temperature range: -65°F to 650°F (-54°C to 343°C)
• Maintains elasticity across repeated heat cycles
• Designed for hi-temp engine components and towing conditions

Can I use this instead of a traditional cut gasket?

Yes — the product is intended to form reliable "formed-in-place" gaskets that replace most cut gaskets. It also can be used to coat existing pre-cut gaskets to improve sealing performance and reduce leaks.

• Replaces many conventional cut gaskets by forming a precise seal
• Coats pre-cut gaskets to enhance torque retention and reliability
• Resists migrating or shrinking that causes gasket failures

Is this compatible with modern engine parts and sensors?

Permatex engineered this RTV for use with contemporary engine materials like aluminum, bi-metal alloys and advanced plastics. Its formulation is sensor-safe and resists common automotive and shop fluids to help protect sensitive components.

• Suitable for aluminum and mixed-metal assemblies
• Sensor-safe formulation for modern engine electronics
• Resists oil, coolant and shop chemicals commonly encountered during service

Where should I use the 81409 High-Temp Red RTV?

This gasket maker is recommended for areas that see high heat or heavy-duty loads. Typical service points include valve covers, oil pans, timing covers and transmission pans where a flexible, heat-tolerant seal is required.

• Suggested applications: valve covers, oil pans, timing covers
• Also suitable for water pumps, thermostat housings, transmission pans
• Works well in towing or high-stress service conditions

Who is this product for? Mechanics, fleet maintainers, DIY enthusiasts and anyone working on high-heat or heavy-duty vehicle systems will benefit from Permatex 81409. If you need a dependable formed-in-place gasket that copes with thermal cycling, modern materials and fluid exposure, this high-temp red RTV is engineered to provide durable sealing performance and improved torque retention in demanding applications.