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

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.

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

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.

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.

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.

This stuff is the real deal. I’ve used every lotion and potion under the son to keep rust at bay and I can tell this will help keeping the underside of the truck bed from the cancer than never sleeps. Worth it’s price.

This works great, and easy to use.

Goes on smooth and easy, gets good coverage as I used about 3.5 cans on a truck. Remains slightly tacky even after drying.