Fluid Film, Krown, Rust Control

AceMI · February 18, 2014

Hello guys.

I just ordered my new 2015 3500HD crew cab. I think I take anal retentive to a new level -- the dealer has agreed to take the vehicle off the truck and not touch it. I have a building, hoist, etc. and will do the prep, running board install, etc. I'm quite particular, which is why the fact that my wife talked me into moving back to Michigan a couple of years ago is ruining my life. I think there's more salt / mag chloride brine on the road than there is ashpalt.

On outright terrible days, I'll be leaving the HD parked inside and driving my old 98... but it's unavoidable, it's going to hit Michigan roads in the winter.

With that, I've researched here, there and everywhere different treatments. It seems Fluid Film, Krown and products like Corrosion-X are much preferred to harder coatings like Ziebart. I like the idea of Krown, but do not like the idea of letting them do it as to keep volume and productivity up (understandably so) they drill and plug the rockers, doors, etc. There's no way anyone is coming at my $60k truck with a drill, so unless I can get the product myself - I think that's out.

I'm leaning towards Fluid Film, but I have two concerns:

1) I've read conflicting reports that it penetrates and dissolves the factory wax coating (NoxRust.) Others say they've not had that problem when using it.

2) I can't click off my need for clean and will still be washing the undercarriage. I'm worried Fluid Film will be more succeptible to washing away.

How many have first hand experience with Fluid Film and can ease or confirm my concerns?

Any other alternatives out there?

Thanks in advance!

amc31b · February 18, 2014

I have used both CorrosionX HD and Fluid film on my truck and other vehicles. While I really like fluid film, I can't recommend it for our trucks. The fluid film did seem to soften the noxrust coating and the areas that the noxrust was already damaged, the fluid film made it fall off almost right away. I am thinking that the noxrust coming off is going to happen anyway but the fluid film did seem to soften it and speed up the process.

If I could do it all over again, I would just rinse your undercarriage at least monthly and call it a day. Just do your best to keep everything rinsed with fresh water and it will be fine. Use a wide fan (gentle) pressure washer held far away or a fairly strong garden hose to rinse and you will be fine. If you want to go above and beyond, order a few cans of the noxrust from the parts counter at the dealer and touch up all the areas that have fallen off. You probably wont have to do that for a few years though. It took my frame about 2 years to have noticible bare spots.

Several years down the road (probably 10 or more), you could begin a process of scraping off any loose noxrust coating and applying a permanent solution like chassis saver. While this process is time consuming, it is fairly easy to do yourself and you would only have to do it once. The GM trucks really do need a new rust protection system. The stupid Noxrust coating is one of the real downsides to the GM trucks overall. It is tacky to the touch and collects dirt, gets scraped and damaged easily, chemical resistance and overall durability are very poor.... Just not a very good product from what I have seen.

AceMI · February 18, 2014

amc - you're absolutely right. I just heard back from Fluid Film and they do NOT recommend it on the GM trucks because of the waxy coating - they confirmed it WILL dissolve it. It's intended to be applied to bare metal. I appreciate their honesty - I couldn't pull similar information from Krown, but Krown is petroleum based, so I have little doubt it would destroy the noxrust.

I'm leaning towards Amsoil HDMP as it's wax based -- if I end up doing anything.

Hopefully that helps someone.

2017SierraSLT · February 18, 2014

I use the Fluid Film. I do not spray in on the frame. I sprayed it on all of the other painted surfaces under the truck with excellent results to this point.

amc31b · February 19, 2014

amc - you're absolutely right. I just heard back from Fluid Film and they do NOT recommend it on the GM trucks because of the waxy coating - they confirmed it WILL dissolve it. It's intended to be applied to bare metal. I appreciate their honesty - I couldn't pull similar information from Krown, but Krown is petroleum based, so I have little doubt it would destroy the noxrust.

I'm leaning towards Amsoil HDMP as it's wax based -- if I end up doing anything.

Hopefully that helps someone.

I used Amsoil HDMP on my dad's jeep wrangler and have experience with too. It is very waxy but it is also petroluem based and will react poorly with the Noxrust coating, dont do it. I really recommend you just not undercoat these trucks. The frame has the noxrust which falls off easily but the sheet metal is galvanized and painted steel so it is pretty protected. Fluid filming the galvanized parts is pretty much a waste of time. The cast parts like the differential, axles and control arms usually come from the factory with a light surface rust which is just cosmetic and wont really get worse over time. The parking brake cable and brake lines are stainless steel but it wouldnt be a bad idea to keep an eye on them over the life of your truck.

If you really want, seal all the cast parts with a durable paint undercoat like Chassis Saver, POR-15 or Rust bullet. After that you can buy a can of noxrust from the dealer and touch up any spots that fall off over time. As far as general maintainence for our trucks, just rinse the under carriage thoroughly once every few weeks if you live anywhere in the salt belt. Don't over think this and don't worry about it too much.

If the corrosion issues really worry you, there are a few options. 1- Get rid of the truck and don't buy gm trucks till they get a different rust prevention system going. 2- Remove all of the waxy noxrust crap chemically (easy off oven cleaner) or mechanically (sand blasting) and then treat the frame with a coating of your choice, IE powder coat, chassis saver, line-x or whatever.

Overall, I think most people are worrying about this issue a little too much. The rust that happens when the noxrust falls off is just surface rust. The rust does not usually penetrate completely through the metal and actually weaken the frame in any way. I am just as anal about my truck as the next guy but some people are letting the sight of surface rust kill their enjoyment with the truck. Then you get the ranting and raving about how much money they spent on the truck, how GM took the tax payer bailout, Goverment motors making crap again, yada yada yada... None of it is necissary, just take a chill pill guys... These GM trucks have similar or maybe even less issues than the other truck brands do. Go to Dodge, Ford, Toyota and Nissan forums and look around, none of them are perfect!

TJMaine · February 20, 2014

In Maine alot of us use a combination of Transmission fluid and motor oil... Cheaper the better ( you can use K1 heating fuel inplace of tranny fluid but you will smell it everywhere you go. It's not LEGAL to do this in Maine but it IS the best route to take as it's fluids that are on your truck from day one and wont ruin or harm other coatings.

Bent-1 · March 16, 2014

I've seen numerous 7-10 yr old GM truck frames with that wax crap on rusted out frames. The best is to strip it off & paint on with Rost Bullet or an epoxy paint.