Underbody Rust Protection

I have a 2010 double cab w/ 120,000 miles that is in great shape all around. However, last year I noticed some areas of surface rust showing up and growing around the truck. So far it's on spots like the tailpipe, trailer hitch, lug nuts and small, small specs on the inside of the tailgate. The frame thankfully remains spotless.

I live in Spokane WA, which has a real winter and I imagine there is some sort of salt going onto the roads (not to the level of the midwest hopefully).

This is nicest vehicle I've ever owned and my intent is to have it for many, many years. So I am curious if it is worth doing some sort of underbody undercoating protection to the vehicle? I don't know much about those processes and how effective they are for my scenario, so any insight would be great.

Ziebart and Line-X are the local options for this type of service.

 

I live in the rust-inducing north east. My husband and I woolwax under our trucks every other winter and wash our vehicles every week or two, including hosing the crap out of the underside. So far so good. We both bought vehicles from the south and coated before they ever saw the salt.

 

Noxudol for me. Had to reapply it lightly after 4.5 years, mainly because I offroad and pressure wash it frequently. 700 inside frame channels, 1600 outside.

 

I treat any visible rust with Corroseal and then spray the underside with Fluid Film Black before the winter.

 

So many options, it gets down to different types of protection. I have sprayed my 60 land cruiser with
Cosmoline 342 spray. It's a military corrosion protectant. I get 12 cans for about $200. It's a solid over
steel/light rust spray. I brushed the worst off with elec grinder and wire wheel.
It's not inside rockers or frame but this truck doesn't see winter.
The higher quality woolwax inside doors, rockers, frame is the way to go for prevention.
@Downytide went full blown dry ice and spray from Honeyseal.ca, I plan to do my classic BJ74
and may do a lesser version for my 2010 RCSB. Maybe he can post a before and after here.

Either way, get it done by a pro make them explain exactly what they are gonna do

 

POR-15 for me. Two coats and then a top coat for anything UV exposed. Touch up every 5 years or so. Works so well that my truck frame now only rusts from the inside out.

Not sure if I should be laughing or crying.

 

That's why I tell people to have a pro do it, they get paid to get dirty and do the inside stuff. I like POR15 but it's not
what I'd recommend for anti corrosion because its limited uses and limitations.

If you want to DIY try this site.
Eastwood Auto Restoration Supplies - Eastwood Auto

 

Yes sir, this is more or less cosmoline coating, the truck was Krown annually but I noticed surface rusts showing and I rinse the truck weekly in winter, I was less than happy with how Krown has turned out (used to be great)

Honeyseal did an amazing job, the only thing was it smelled for days, but the pictures speak for itself, truck is 4 yrs old, my daily driver go through typical Canadian winter.

before:




After dry ice and acid spray


After seal is sprayed:

 

I think my 2010 is getting treated in the spring. In May 2026 post a pic, lets see how it holds up.
I have no doubt. It was a series of pics over 8 yrs of the guy with an 80 series land cruiser out of Minnesota
that sold me on Cosmoline, done every 2 yrs and driving all year round.

 

Unfortunately I didn’t find out about the Eastwood anti-corrosion spray for frame internals until 15+ years later after ownership. Would have been nice if I did as Toyota only accelerated the problem applying their Noxodul 700 stuff over existing internal rust which did nothing but exacerbate the problem. That and by plugging the drain holes and sticking foam in one end blocking the opening to the frame rails.