GMC rusty frame

I have a 06 GMC 2500 that is started to rust on frame. I just had to replace diesel fuel lines and brake lines. The garage said to spray underneath with Fluid Film. I heard FLUID FILM IS WATER SOLUABLE. If this is true it doesn't seem it would last long. They use the liquid salt on roads here in Maine. I was thinking of using POR paint but very messy. Has anyone use any undercoat to stop rust? Thanks for any help.
 
The worst part is prepping the frame---ALL rust dirt oil and loose paint has to be removed before applying any sort of rust proofing. POR 15 or any good rust paint will work on a clean frame; once dry then oil or undercoat every year.

Ben
 
The name Steve in Maine says alot, i have taken those $9 garden home depot etc and spray used motor oil cutting if need with diesel
and spray down the whole underside yearly lay it right on jusy trying to buy some extra time, its all planned obsolescence.
link
 
http://www.fluid-film.com/spraying/
I use Fluid Film on some cars and it stays on pretty good.
I sprayed inside the doors and 2 years later I can see where it is still creeping out over winter.
If you have ever used 3M Rust fighter I or what the English call wax oil , it is somewhat like that.
 
Steve,I also live in Maine and my friend runs a one man garage and has sprayed that stuff on some cars.We both think it is a waste of time and money.What he has been doing is wash the underneath of the auto let it dry good and then spray with used motor oil.Seems to do as good a job as anything.It should be done once a year to keep it up. Good luck NEIL
 

That is a good question. I worked on a 08 chebby this week that was undercoated, when I don't know. The undercoat job looked to be applied very well and has some age to it. Rust is popping the undercoat off :shock:

I don't know how you can beat oiling it down I have tried different stuff oil win's out every time... The fertilizer hopper on my Farmall will rust they all do. I have coated it repainted it Por-15 it, Por painted any paint it, it will still rust... The best is to hose it down let it dry and apply thick gear oil to it...

I am a fan of Por-15 for a fuel tank and go the extra mile to insure a clean surface to apply it too... Maybe I did not go the extra mile on the fertilizer hopper :oops:. I have went the extra mile on other metal using Por paint for rust it did not hold up any better than cheap rattle can paint...
 

Applying a coating over rust, even POR15 is just creating a better environment for the rust to work. I agree with just pressure washing it as well as possible then applying an oil coat, except I add one step. I spray WD-40 any place where moisture could be trapped, let sit a day or so then spray oil on.
 
Texaco used to have an under coating that was like a grease, I think it had a wax base. It held up very well.

Dusty
 
yes, that's correct ! I had a car in the 60's that had been undercoated. When cracks in the coating happened, water(and salt) got in there and was held against the body metal.
soon I had big holes in the body.
 
When I was a GM salesman 20-25 years ago, on new GM vehicles it said right in the owner's manual that undercoating would void the rust through warranty.

We had an over eager salesman who sold a little old lady an undercoating package on a new car to make more money on the sale. She wasn't as dumb as the salesman thought. She came in the next day and pointed out to the salesman the paragraph in her owner's manual that said undercoating would void the factory rust through warranty.

Upshot was, the dealership had to refund her the price of the undercoating and give her an identical new car that wasn't undercoated, since you can't remove the undercoating. I'm not sure what ever became of the undercoated car, I switched jobs about then. They probably dumped it on an auction or sold it to someone who was too dumb to read the owner's manual.
 
I just took the plates of my 1990 F150 as it was hard to keep steering it to stay in the lane. Mechanic told me there was so much rust that it would not be cost effective even it was possible to repair. Less than 100,000 miles on it. Last ten years was an emergency sit around vehicle.

Undercoat made a big difference in gravel noise on Dad's 1950 Chevy.

IaLeo
 
I am driving a 2003 Dodge 2500 that I bought new with absolutly no rust. I have always had it oil undercoated every year. Here in Ontario there are lots of small shops that spray it on and drill holes to reach areas like door sills and tail gates. Some of it looks like ATF or chainsaw oil. The good thing is ,oil sticks to rust so that usually ends the rust.
 
An interesting discussion here.

I think we are talking about 2 different types of undercoating, the tar type and oil.
 

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