Cosmoline RP-342 Black Rust Preventive Spray (Military-Grade) 6-Cans

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.

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.

Prep was the key to this working great. I used a steel brush and removes all the loose surface rust on my 2013 Chevy Tahoe. I then used a salt brine remover and cleaned the undercarriage twice with it to ensure I got all the salt off. I then sprayed a gallon of simple green degreaser (you can use any degreaser) and used a garden hose and sprayed it all of thoroughly and let it dry for 24 hours before applying Coroseal with a 1 gallon garden sprayer over the entire undercarriage with a nice even coat. I let it dry for another 24 hours then applied this black Cosomoline. It covers well and dries rather quick. I used all six cans to thoroughly and liberally coat the entire frame and various other high wear undercarriage areas. Be aware that even after it has “dried” it is still tacky/sticky as it is wax based but will not come off easily. I highly recommend this product but make sure you do your prep work.

I wish it didn’t smell, but it is Cosmo. product works. Great coverage awesome!!!

Coated well, several of cans had issues spraying.

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.

Was using 3m undercoating but did not seem to hold up,this stuff different story,it is very good,sticks well,1 can covers quite a bit of frame.Highly recommend. Just wear protective clothes, overspray does get on arms and clothes, be ready to throw them out when done under vehicle....but this stuff is fantastic.

This stuff looks good and works well