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    • Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon)
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  • RP-342 Military-Grade Rust Preventatives
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  • Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon)
  • Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon)
  • Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon)
  • Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon)
  • Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon)
  • Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon)
  • Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon)
  • Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon)
  • BULK: RP-342 "BLACK" Rust Preventive Spray
  • Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon) Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon) Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon) Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon) Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon) Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon) Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon) Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon) BULK: RP-342 "BLACK" Rust Preventive Spray

    Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon)

    MSRP:
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    Now: $119.95
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    Availability:
    COMING SOON - Available October 24th.

    Expected release date is Oct 24th 2025

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    Product Description

    Cosmoline RP-342 "Heavy" Military-Grade Rust Preventive Spray
    Our Strongest, Longest-Lasting (and Fastest-Drying) Rust Preventive Spray, PERIOD!

    SEASONAL NOTE: While RP-342 has thousands of rust-preventing applications, Vehicle Undercoating is the most popular come this time of year. For undercoating-specific information, please visit our RP-342 Undercoating FAQs page for some helpful tips.

    * Offers the highest concentration of Industrial-Grade Cosmoline® available in a convenient Aerosol Can (now in Bulk).
    * 1-coat protects all metals, iron, steel (stored Indoors or Outdoors) for Years!
    * Newly formulated! Our thickest, longest-lasting Rust Preventive Spray.
    * Produces dry-to-the-touch, amber translucent (see-through) petroleum wax coating.
    * Faster-Drying formula allows for quicker handling and/or shipping.
    * Withstands severe outdoor exposure, salt-laden atmospheres, acid & caustic fumes and other damaging environs.
    * Repels water and will not wash off in salt water environments.
    * Will not crack, craze, peel or flake and remains slightly flexible over time.
    * Exceptional Vehicle Undercoating Product (Autos, Trucks, Buses, Trailers, etc.) - Road salt, debris and chemicals - No Problem!
    * Aggressively adheres to imperfect surfaces and offers self-abrading characteristics.
    * Modeled after Military Specifications: MIL-PRF-16173, Grade 4 and MIL-C-83933.
    * Trusted since World War II. Our Bestselling RP - commercial customers, US Armed Forces, Government & Do-it-Yourselfers.
    * Your Satisfaction with this product is Guaranteed!

    COMMON APPLICATIONS INCLUDE (but are not limited to):

    * Vehicle undercarriage / undercoating (cars, buses, trucks, etc.) - 1 coat can protect for years! See Undercoating FAQs.
    * Parts & equipment storage
    * Overseas transportation
    * Heavy machinery & equipment
    * Packaging
    * Dies, molds, lathes, shafts and beams
    * Offshore Drilling equipment, platforms & infrastructure
    * Farm implements
    * Boat shafts and propellers
    * Marine fittings
    * Rifle & other firearms preservation/storage
    * Garden tools
    * Lawn mower blades
    * and any other surface or part that might rust on you...

    DOWNLOADS:  Product Data Sheet / Overview     RP-342 Safety Data Sheet (SDS)        


    APPLICATION:

    Make sure surface is reasonably clean and dry (not oily or greasy). Spray a single generous, uniform coat.  Complete setting of protective coating takes approximately 1-2 hour after spraying.  Typical first application Dry Film Thickness is 2.0 Mils (51 Microns)

    REMOVABILITY:
    RP-342 "HEAVY" can be removed with any over-the-counter petroleum solvent. Examples include mineral spirits, paint thinner, naphtha, diesel fuel, or our very own Cosmoline Remover.  We believe our Cosmoline Remover is the most effective removal solution by far.

    MILITARY SPECIFICATIONS:  
    RP-342 "BLACK" is modeled after the following military specifications: MIL-PRF-16173E Grade 4, Class 1 and MIL-C-83933

    * Certificates of Conformance are not available for this product. 

    SHELF LIFE:
    18 Months when stored in prudent conditions (cool, dry, shaded).

    ENVIRONMENTAL NOTICES:
    * Ozone Depleting Substances - Aerosol products were not manufactured, do not contain, and were not packaged using any Class 1 or Class 2 ozone depleting substances as defined by the clean air act.  
    * Non-Chlorinated (no chlorinated solvents).

    Product Videos

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    • Cosmoline RP-342 - Vehicle Undercoating Overview

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    Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon)
    Cosmoline RP-342™ "BLACK" Military-Grade Rust Preventive & Undercoating (by the Gallon)

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    CANADA

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    UNITED STATES
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