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Black cartridge of RTV gasket maker paste, 300 mL

Loctite

Loctite 135508 RTV Gasket Maker 300 mL Black

SKU CH-8F00-GD2CT

Black RTV gasket maker fills gaps up to .02 in and withstands -65 to 500 °F

  • Withstands extreme heat up to 625 °F
  • Remains flexible in cold down to -65 °F
  • Resists oil and automotive fluids reliably
  • Cures at room temperature in 30 minutes
  • Fills gaps up to 0.02 inches precisely

Loctite 135508 RTV Gasket Maker

Loctite 135508 is a room-temperature-vulcanising silicone paste designed to form flexible, oil-resistant gaskets on metal flanges. It suits mechanics and technicians who need a reliable seal for automotive fluid systems without pre-cut gaskets. The black cartridge fits standard caulking guns for controlled application in workshop or garage environments.

300 mL cartridge fills gaps up to .02 in

The material bridges gaps up to .02 in and cures fully in one day at room temperature, with a 30-minute working window for assembly adjustments. It withstands continuous temperatures from -65 to 500 Degrees F, covering alcohol, anti-freeze and automotive fluid exposure. Joints requiring larger gap fills or instant load-bearing will exceed its capability.

Series SI 598 formulation resists oil and fluids

The SI 598 chemistry provides resistance to oil, anti-freeze and alcohol-based fluids, eliminating the need for separate sealant additives. Supplied as a 10.14 fl oz cartridge, it is ready to use with no mixing required. The product carries a California Proposition 65 warning for reproductive-harm chemicals.

How it compares

Measured against everything we stock in Caulking & Sealing Supplies, at today’s prices. Recalculated every night.

Price $34.99
Pricier than about 72% of the 631 comparable items (median $16.99).

Specifications

Product
Brand nameLOCTITE

Questions about this item

Will the Loctite 135508 RTV seal effectively against the aluminium timing cover and steel bolts on my older engine?

Yes, the paste is formulated for metal surfaces and resists oil, anti-freeze, alcohol and automotive fluids across a -65 °F to 500 °F operating range.

How do I know the SI 598 gasket maker has cured properly after assembly?

The product reaches full cure in one day at room temperature; after that time the black paste becomes a firm, flexible rubber that does not feel tacky and holds its shape in a 0.02 in gap.

Does the 300 mL cartridge include a nozzle or do I need a separate caulking gun?

The 10.14 fl oz cartridge is a standard caulking-gun tube; a gun and any desired nozzle tips are sold separately.

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