40 y o car has been hanging in there with tar based undercoating because I annually inspect and touch it up. How can I use Fluid Film with its superior wicking properties? Or just stick with stone-age rustoleum rattle can rubberized undercoating?

 

Tell us more about "Fluid Film". Season of the salt is about to start here.

 

first, let me start by declaring i'm a dinosaur - sometimes a bit slow to change my ways and thinking with "some" things. i haven't used the stuff, myself, but i did hear about it a while ago on a YouTube channel i'm subscribed to. it piqued my interest ever since and i actually plan to buy some and give it a try. i was led to believe that it doesn't dry/harden though so i, myself, would be apprehensive about using it as an undercoating, but with that said, they say it can be used as an undercoating. so there's that.

https://www.fluid-film.com/automotive-applications/

 

Write up says it may effect existing undercoatings.

My FD seems to have some sort of factory or dealer undercoating already.

Also says it may cause rubber components to swell. That might actually be good for old bushings?

 

It's a magical non drying coating that when a rock hits it, it doesn't crack, but instead magically flows back and repairs itself. Woolwax is supposed to be better. (I saved you several hours of watching youtube vids)

The dinosaur based tar coatings do not flow back. Instead, they allow water and salt in, which corrodes the underlying steel year after year after year. If you check the undercarriage annually, you can stop it when the rust is just beginning.

I did the dinosaur thing, and my car survived 4 new jersey winters. the rest of the time was spent in s. cali and the deep humid south.

 

I agree that with the old stuff, it can make things way worse over time if there is no upkeep. I am using Corrosion Free currently on my daily driver. Similar to the other that wick and self heal. It lasts about 18 months but I reapply every year. What is really important with the wicking type is to also apply it inside the rockers and other channels. Some of these application systems have a long wand to get deep in there. I just remove the rubber grommets and spray liberally. When it gets wet, it spreads even deeper into those spaces.

I live in Pennsylvania and I looked for a car in areas without salt, found one in Oklahoma. I was told sand is used when needed. The least rusty 10 year old car I and others ever saw, still rockin' the 2006 exhaust. Speaking of which, don't get the stuff on the exhaust. I have used it since 2017 and so far so good. After you see the first rust bubble on the rear quarters or rockers, the car is about a five year ticking bomb here in West Pa.

When redoing areas people have been using POR 15 on the outside. What will happen with those is that the inside of the channels will rust badly if left untreated. It will look perfect on the outside but wack it with a hammer and it just comes apart in places. Not much holding it together except the POR 15.

I might switch to fluid film as it is easier to get or have applied.

 

I was told the Corrosion Free is good for bushings, not sure if that is actually true.

 

fluid film over tar undercoat make a big mess?

spray fluid file just inside the rockers (frame rails) ?

anyone know?

 

Liquid Wrench on my noisy rear bushings worked to eliminate the clunk for a while.

 

Very good questions, not sure though. Different companies use different formulas. I would just read the website for overspraying rubberized unercoating. There are videos for fluid film on the interwebs. I thought I saw them do both inside and out, I could be wrong though.

For Corrosion free it is spayed everywere underneath and inside as much as you have access to. Better reach with a long spray wand though.The place that sprays mine just does the surface underneath and a few other places as far as I can tell. I go back and spray the cavities.

 

How did it work out?

Was Corrosion Free sprayed over tar undercoating?

I ran over a curb leaving holes in the body on lower rear wheel wells. Cleaned and primered, and tried to use Bondo-Glass to fix. The stuff keeps dropping out of the holes before it hardens. Should have used Great stuff expanding foam, or something.

I stuck a water hose up the cavity, and a ton of crap came out, and this was just 3 months after running over the curb.

 

So far, so good.

If there is tar undercoating on a 2006 Acura TL, then yes. Otherwise, There is a coating in the wheel wells though that is sprayed over.

I am sorry this happened to you. Hopefully you and/or everyone in the car is ok. I am not a body man by no means. I did see where old school non body men will attach a piece of screen or metal and bondo over that. Looks terrible but it works, not sure for how long though. Foam works but holds water if I am remembering correctly. If this is a car you plan on keeping, I would strip the entire wheel well and check for further rust. You will be playing a game of wack-a-mole with rust, coated with fluid film or not. Pull out the stuff in trunk and stick a light in there, look for rust on the back side of the wells. If there is, not much to do except replace or hope and pray. If fluid film or others have Phosphorus? it can eat some of that rust in there and maybe buy you some extra time. Rust Kutter is one I have seen with a high Phosphorus content, still no magic bullet.

 

The exposed metal was shiny, so rust didn't have time to form in the nonvisible areas. I sprayed primer rust primer into the hole, so things should be good.

Gonna take another whack at bondo-ing the holes tomorrow.

Sure wish I thought of expanding foam.

Shining a light into the cavities is a good idea