In my area, to my knowledge, "undercoating" was paying a company to coat the under body of the car in some form of rust/salt/moisture resistant material (something along the lines of POR15). Once applied, you would not have to worry about having it re-applied for a long time if ever. Now, this is coming from a guy (me) who has NEVER had a car under coated, so don't take my word for it.
But some parts of Canada I believe are just brutal on cars due to harsh winter conditions and salt that results. I saw a YouTube video of a Grand Prix owner having to change his oil pan on a 3800 as it rusted through!!! Since he had to order one, he first used JB Weld to "band-aid" it until the replacement came in. Very, very unheard of to have an oil pain rot out in my part....

 

I sell lots of oil pans! And that is why. And these cars are notorious for it. So are Taurus and other 3.0L Fords. And Caravans. Maybe its just the common cars.

If I was a guy in North US - say MI or NY - I'd be thinking about opening a business doing oil spray. Seems like there is a market for it to be cornered! It would take much expense. It is a dirty job.

POR15 is good stuff, but its supposed to be used on clean metal. POR15 does make a metal prep for that. But it would wreck havoc on things like chassis parts which need to be serviceable and removable. POR15 is a hard plastic-like coating. Oil spray goes into you door jams. Its good to spray on pretty mauch any moving parts like hinges. It even help keeps nuts and bolts serviceable.

I gotta figure out how to market this in the US. Maybe this can be my ticket out of this country!

 

my friend had the same issues with his 2000 monte.......plastic air dam below the rad support tend to trap water and rust it out....as far as the frame rails he had the sheet metal shop make one up and had it mig welded in sprayed it with rock guard.....it was rotted out by the brake line brackets....bottom of the rad support he wire brushed it and put 3 or 4 coats of roofing cement on it and took the plastic air dam off.....but it's solid and passed inspection....that was 2 yrs ago and it passed for the second time since then....but the brake lines will probably snap if that's the side that's gone....he only drives it summer months but it's holding up quite well

 

My oil pan is actually starting to rust a little. I know the gasket leaks too. But you have to drop the frame to fix.

Maybe I will actually fix that at the same time

 

maybe he knows how to fix your rust problem lol even though his specialty is 5th gens...maybe he wants to move on to the younger crowd?

 

I hate you. lol

 

I am actually surprised to hear your car rusted out as it's a 2000. That 12 years but still. Did you do rustproofing over the years? My 95 Z34 which I got rid of just recently was okay rust wise overall and that was 17 years old and did winter driving every year. I did park it in a garage but I heard that can activate the rust even more.

 

i am still suprised because the way the monte lookes that chibi has i would think the under side was kept crystal clean as well it still gets me off guard. to know how the condition is it still bites a big bite from 7 eleven horribly

 

I kept it as clean as I possibly could, winters just suck where I'm from, and everything Brent has been saying is so foreign, I wish I knew about it 10 years ago.

 

i know i also know you kept it super clean much as possible as well i have a feeling you also had the bottom clean as well for the road salt during the winter. what i mean didnt let it sit with salt all over the car. it is to way to nice to know you let it like that. i have a feeling you will figure some thing out to be honest. on the bright side you probably have a project vehicle persay. when every thing gets agrevated you will probably work on it. as in take it apart in the garage and just look at it and label every thing where every thing came off. when every thing gets frustrating. that is what i am doing with that cougar keep it looking nice got in a accedent that wasent my fault right now i am sighing because it is mainly cosmetic. and the radiator core suport also needs to be replaced. i am just sighing away i enjoyed that car as well you enjoy your monte. it will work it self out. and i hope you will take your time because you have alot on your plate persay. i wish the best because of the other things that you are saving up for. i really mean it i hope the best and hope you will figure it out