Best undercarriage rust stopper/sealer

[jeredcollins]

Done a lot of research on the topic and it seems there are a lot of products out there. The majority of people either swear by Fluid Film or POR 15.

Fluid Film Pros:

Gets into crevices much easier and better
Cheap
Less prep time

Fluid Film Cons:
Isn’t a paint and needs to be reapplied periodically (especially if you spray your underbody in a car wash)
Doesn’t “freshen” up the undercarriage like a paint style rust stopper does


POR 15 Pros:
Longer lasting
Better looking (new car look)

POR 15 Cons:
Lots of prep work
Doesn’t get into crevices or cracks as well
Expensive

My 4runner doesn’t have a lot of rust but I definitely want to keep it in pristine condition. What do you guys think?

 

[kolelt]

Salt�� I’ll keep it short.

Fluid film is basically greas. Keeps water and salt away from steel. Stays on 4-6 months depending on how often you wash your undercarriage. It is not the same as por15. It does not really stop rust if the area is already rusted. It basically prevents clean metal from starting to rust.

Eastwood heavy duty grease is like fluid film. But slightly thiner and much more sticker.

Por15. Is a rust treatment product. Then after you have fixed it. And treated it with por15. Then you apply fluid film on top.

From expiernce.

 

[MN4runnerman]

Por15/chassis saver as a basecoat. Then fluid film or what I do is use 80w90 gear oil and spray it. Recently I’ve tried an aerosol rust converter made by 3m and then used valspar anti rust black enamel spray can as a topcoat. Then sprayed 80w90 on top of that. The reason I did that is because the recommended time between coats for por15/chassis saver is 4 hours. I just didn’t have the time to use that stuff.

 

[silver4est]

I do not have any personal experience yet but I have been reading really good reviews about Krown coating. they spray the frame inside and out and inside body panels.

https://www.krown.com

 

[Kanoe]

Por15. Is a rust treatment product. Then after you have fixed it. And treated it with por15. Then you apply fluid film on top.

As stated, it is NOT one or the other but rather both. Clean up the rust using a paint product such as POR-15 first, then before winter coat the cr*p out of it with a grease/oil product. That is your best bet for success.

Have fun.

 

[biggestmexi]

This is what I used. I haven't been under it again since I did but I am waiting for winter to get over to check it out.

I put the truck up with a lift and used an angle grinder and twisted wire cup brush head that removed a lot of rust, but was messy.

 

[kolelt]

I always say. Ever notice a car that oil has been dripping for years. Or oil leaking from something. That area, always has clean metal under it. It looks like dog shit. But it’s rust free.

Another issue is, it’s hard to see behind that metal.

 

[raKnizek]

Fluid film worked wonders for me. Like already mentioned it wont convert rust but it will help slow down rust thats already there. However it is best for putting on top of rust free surfaces. More of a preventative maint.

Another con worth mentioning is that your vehicle will be a bit messy to wrench on.

 

[jmferg]

I cleaned the undercarriage, applied rust converter the flaky areas, duplicolor bed-armored the frame, then before winter used 12 cans of fluid film inside and outside of everywhere including body panels.
I don't have any pictures of the fluid film but that goo is everywhere.

Sent from my iPhone using Tapatalk

 

[ivopivo]

I've been testing a few products last 1-1.5 years at my shop. We didn't want anything black that hides stuff, including rust, so we tried a few different products.
Fluid Film (regular stuff at Lowes etc) is great but won't last too long.
Fluid Film AR is much thicker and lasts for years, holding up well on both my 4runner and 330i after 6-10k miles on each after about 1 year on BMW and 6-7 months on 4runner.
My favorite... Amsoil Heavy-Duty Metal Protector. This stuff won't creep into crevices like their old metal protector (they changed the HD formula somewhat recently), but is still very runny before it dries. Once it dries it's tough to get off. You won't simply wash it off, rather have to use mild chemicals. I put it on my BMW wheel spoke and it won't wash off after 10+ washes and 6-7k miles.

I used the Amsoil HDMP on my 4runner VERY liberally in all the panel drain holes, frame, etc. It looks like day 1 still so I'm very impressed with that.

 

[MN4runnerman]

My favorite... Amsoil Heavy-Duty Metal Protector. This stuff won't creep into crevices like their old metal protector (they changed the HD formula somewhat recently), but is still very runny before it dries. Once it dries it's tough to get off.

That stuff is called cavity wax. Great stuff. I use the 3m brand of it but it’s all the same. 3m sells 3 different length spray nozzles that spray, I think, 360*.

 

[albertschmitz]

This is what I use ... https://www.theruststore.com/Rust-Converters-C10.aspx