Permatex 81878 Ultra Copper High Temp RTV Silicone Gasket Maker, 3 Oz

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Designed and recommended for post-1980 4-cylinder, turbocharged or high performance engines, more oil resistant than conventional silicones more flexible than cut gaskets, non-flammable, non-toxic.
SKU: 40305123
MFG: 81878
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Permatex gasket makers offer significant performance advantages which include outstanding oil resistance, excellent torque retention and hi-temp, sensor-safe properties. Extended warranties, engine sensors and new component materials such as aluminum, bi-metal alloys and high-tech plastics, have created the need for superior RTV silicone gasket makers in both OEM production and service applications. Permatex always has the right gasket maker for your application.

The most advanced, high temp RTV silicone gasket available. Sensor-safe, low odor, noncorrosive. Superior adhesion. Three times more oil resistant than conventional silicones; eight times more flexible than cut gaskets. Temperature range -65°F to 700°F (-54°C to 371°C) intermittent; resists auto and shop fluids and vibration.

Permatex Ultra Copper is a single component, room temperature vulcanizing gasketing compound designed to provide reliable “formed-in-place” gaskets for mechanical assemblies. This material cures on exposure to moisture in the air to form a tough, flexible, silicone rubber gasket. The product resists aging, weathering and thermal cycling without hardening, shrinking or cracking. Designed for the higher temperature environments encountered in 4-cylinder, turbocharged, and high performance engines. Permatex Ultra Copper is the most advanced high performance, high temperature (up to 700°F intermittent) RTV gasket available. OEM Specified.


  • Sensor-safe
  • Oil and gas resistant
  • Designed and recommended for post-1980 4-cylinder, turbocharged or high performance engines
  • Low odor, non-corrosive
  • Superior adhesion and flexibility
  • Can be used as a gasket maker or dressing
  • Non-flammable, Non-toxic
  • More oil resistant than conventional silicones; more flexible than cut gaskets
  • -75 to 700 degrees Fahrenheit intermittent temperature range
  • Resists auto and shop fluids and vibration
  • Carded


  • For Automotive: Exhaust manifolds/headers, valve covers, oil pans, timing covers, water pumps, thermostat housings
  • For Motorcycle: Exhaust header flanges, slip fit exhaust pipes, and muffler end caps
  • For Marine: Exhaust manifolds/headers, valve covers, oil pans, intake manifold end seals, water pumps, exhaust tubes


  • Chemical Type: Oxime silicone rubber
  • Appearance: Copper colored non-sag paste
  • Flash Point °C (°F): >93 (>200)
  • Size: 3 Oz
  • Type: High Temperature
  • Packing Type: Tube
  • V O C Content: 3 %
  • Odor Scent: Low odor
  • Form: Paste
  • Drying Time: 24 hr
  • Applicable Materials: Aluminum, Brass, Iron
  • Application Time: 2 hr
  • Standards: OEM Specified
  • Odor Scent: Mild
  • Flammability Rating: 1
  • Composition: RTV silicone, poly hydroxy, modified silicon dioxide
  • Specific Gravity: 1.05
  • Extrusion rate @ 25°C, (grams/min): >300

Typical Curing Performance:

Permatex Ultra Copper Hi-Temp RTV Silicone Gasket cures on exposure to moisture in the air. The product dries tack free in one hour and fully cures in 24 hours. Cure times will vary with temperature, humidity and gap.

Chemical / Solvent Resistance:

The product retains effective properties in contact with automotive fluids, such as motor oil, transmission fluids, alcohol and antifreeze solutions. Note: Not recommended for parts in contact with gasoline.

General Information:

This product is not recommended for use in pure oxygen and/or oxygen rich systems and should not be selected as a sealant for chlorine or other strong oxidizing materials.


MFR: 81878
SKU: 40305123
UPC: 686226818782
Brand: Permatex