







🛡️ Lock in legendary rust defense—because your gear deserves military-grade protection!
Cosmoline RP-342 is a military-spec, fast-drying rust preventive spray that delivers a durable black petroleum wax coating. Engineered to protect metal surfaces indoors and outdoors, it resists salt spray, extreme temperatures, and harsh environments for years with just one coat. Trusted by the U.S. Armed Forces and professionals since WWII, this aerosol spray offers effortless application and long-lasting corrosion defense across thousands of industrial and personal uses.
| ASIN | B0888PB5G7 |
| Best Sellers Rank | #54,306 in Automotive ( See Top 100 in Automotive ) #138 in Care Corrosion & Rust Inhibitors |
| Brand | Cosmoline Direct, LLC |
| Color | Black |
| Customer Reviews | 4.7 4.7 out of 5 stars (186) |
| Date First Available | May 1, 2020 |
| Finish Type | Gloss |
| Indoor/Outdoor Usage | Indoor, Outdoor |
| Item Form | Aerosol |
| Item Weight | 7 pounds |
| Item model number | RP-342 |
| Manufacturer | Flywheel Distribution, LLC |
| Manufacturer Part Number | 342-1032-6 |
| Model Name | RP-342 |
| Package Information | Can |
| Paint Type | Spray |
| Product Dimensions | 5.12 x 6.38 x 9.84 inches |
| Size | 12 Ounce (Pack of 6) |
| Special Feature | Fast-Drying |
| Special Features | Fast-Drying |
| Specific Uses For Product | Vehicle Undercoating, Car Undercoat, Truck Undercoating, Rust Prevention, Rust Preventive |
| Surface Recommendation | Metal |
| Unit Count | 72 Ounce |
B**R
Awesome
I wish I discovered this years ago. Lasts a long time and looks great. I’m done wasting time sanding under my truck and painting. It doesn’t last or protect as well as using Cosmoline. Came out awesome
A**R
This product is all that is needed to rust proof your vehicle !
I did the entire underside of my truck over the weekend. The results are better than I expected. I sprayed it on all suspensions parts, bushings, coated my leaf springs and immediately noticed a quieter ride. I have used Fluid-film in the past on my trucks and liked the results, except that it stays oily/wet to the touch. RP-342 has exceptional coverage and dries to the touch, it also makes the underside of your vehicle look like new ! I have also tested this using my pressure washer, it does not wash off once dry. I can't say enough about this product, I will never use anything else.
S**K
Great undercoating!
I'm a pickup truck guy, and I undercoat every pickup truck I have. Typically I use a lanolin type coating, but tge lanolin doesn't last long. However this stuff, you can quickly see why it is military grade. Thus stuff coats quickly, easily, and we'll. Better yet, this stuff has staying power, it looks and feels like a crayon type wax. One recommendation, invest in a tyvek suit. Thus stuff will get on you, and it takes a lot of effort to get it off.
R**H
Great frame wax.
Tired of liquid grease undercoats that wash off in a month. Looking for something like the original frame wax that was applied at the factory. This stuff is legit. It actually dries, doesnt wash off, and maintains a pliable waxy feel like oem frame coatings. See photo for treated vs untreated.
G**R
Undercoat
Went on great, no problems with cans clogging. Kept them warm till I went to use each can. Did both gladiator and wrangler used 4 cans each went heavy on coatings
T**D
Works great
This works great, and easy to use.
D**N
Great finish, and durable without being too messy
I wire brushed what I could, and applied over all surface rusted areas, and used woolwax with the pro gun to spray inside the frame rails and areas I couldn't get with these cans. The application process is messy for sure. Wear a cap, face shield, respirator, coveralls, and gloves if you don't wanna have it all over you. After it's cured, it isn't too messy to work on the vehicle. It drys to a hard waxy finish and will transfer a little bit if you rub against it, but nothing like grease. Doesn't smell much at all after a few days either. First couple days it had a typical waxy cosmoline smell. I would definitely recommend it for delaying corrosion. Since it's waxy, it won't flake off and trap water like paint can if it fails. I needed about 5 cans for my 04 Tacoma regular cab.
T**Y
The Good Stuff
Love this stuff. Had a frame replaced on Tacoma and this is a flexible self healing material. Will buy more.
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