I've got a 2009 Sport fit that's unfortunately fallen to the curse of Canadian winters - the rear wheel arches are really starting to rust out, and because that particular body panel is spot-welded to the car frame it's not fixable. I've seen a few threads on here talking about the same issues, but I haven't found any talking about how long the cars lasted once it started - in my case it's pretty bad, has been going on for a few years now and the nook at the front of the rear arches is now more Swiss cheese than metal on both sides. It's really a shame, because the car only has ~120,000km and is a joy to drive - I really hope it'll last at least a few years more. Does anyone have any experience with this issue, and how long did your cars last once it began? Thanks!

 

It's almost sure that it is possible to replace the rear fenders. But it is more work, and the cost is high.

You can use any kind of rust proofing stuff to delay the rusting a bit, but for sure it won't go away. I wouldn't use oil as it is too liquid and will wash away quickly. Grease or something like that would be better.

Also, depending on your skills, you could use POR15 and try to fix it yourself.

Pictures would help to see how bad it is.

 

Frenzal has it right. Anything can be fixed if you're willing to spend the money.

As a somewhat recent price point, a while back I got a screaming deal on my wife's car (2014 Nissan Leaf EV) because the paint was in desperate need of compounding and polishing (I did that myself and it's shiny and reflective again), the interior was filthy (another DIY project), and one rear fender lip had a bad rust spot that was about the size of 2-3 quarters laid end-to-end.

Getting that fixed at a local body shop cost just under $1300 (US). The work involved cutting out the bad metal, welding in new metal, and repainting and blending the rear quarter panel. I hate rust and was willing to pay to stop it, but this was an expensive repair. Having said that, the car is easily worth double what we paid for it and my wife has free charging at her work so our operational costs are essentially zero. My plan was that I would fix the rust, she could drive it for a couple years, and we would sell it for more than we paid for it even after including the repair cost. She loves the EV and pretty much refuses to drive my Fit anymore because it's so loud and crude.

So, it's been about 15 months since getting a real body shop repair and... the paint is starting to bubble in the same location. I'm not sure if they didn't cut out a big enough margin, if they didn't get the new metal fully sealed with primer and paint, or what. It's quite frustrating and several times I've started to drive to the body shop to see what they can do, but I'm pretty sure they won't do anything as I'm in Massachusetts and stuff just rusts here. I should point out that after the repair I removed all the underbody plastic, cleaned everything by hand, and applied Fluid Film to the entire undercarriage. In the winter I wash my cars and spray the undercarriage as often as possible to flush out the salt, probably averaging three times/month, so I'm doing everything possible in my environment.

Back to your question, you have a couple options from cheap to expensive.

1). Cheap - do nothing. Rust accelerates rapidly, as do your tears.

2). Cheap - wash the car frequently in winter, especially the undercarriage to flush away salt. Rust accelerates slightly less fast over time.

3). Moderate (mostly your time) - clean up the rusty areas as well as possible. Liberally spray the area with something like Fluid Film to seal the rust from moisture and salt. Monitor and reapply as necessary. Rust will slow down considerably but it will still look horrible.

4). Moderate (more time) - clean up the rusty areas as well as possible, including removing flaky rust. Use a rust converter like the suggested POR15 to convert and seal the rust. Liberally spray the area with something like Fluid Film to further seal the rust from moisture and salt. Monitor and reapply as necessary. Rust will slow down considerably but it will still look horrible.

5). Moderate (still more time) - clean up the rusty areas as well as possible, including removing flaky rust. Use a rust converter like the suggested POR15 to try to convert and seal the rust. Watch a bunch of Youtube videos showing people rebuilding fenders using body filler. Convince yourself that you have innate bodywork skills. Do a bunch of sanding and a spray can repaint. Almost certainly be disappointed when the rust comes back in 3-6 months. If I sound sarcastic and like I may have tried this in the past, it's because I have. Put on your 20/20 hindsight glasses and notice that none of the Youtube videos show you what the repair looks like 6 months later after a salty winter.

6). Professional body shop - as described above. Expensive. May not be a permanent fix, but will look good while it lasts. If it doesn't last, you'll scratch your head and say "Wait, I paid $1300 and my wife didn't even notice the rust in the first place?..."

If you just want to drive the car and don't care as much about appearance, go with #4 above. The cost is very reasonable and if you're diligent about flushing away salt and keeping the rusty areas coated with Fluid Film or a similar product you can keep the car going for a long time.

 

Thanks for the advice. Unfortunately, I went to a body shop to see how bad it'd be and they said a lot of metal cutting and replacement would be needed, which means a ton of labor cost (more than the value of the car in Canada). I've attached some pictures to this reply, for both the left and right sides of the car.

Thanks. Yeah, I've been trying my best to keep the car washed regularly, including the underside, but it's still accelerating. I'll look into your suggestions, 3) or 4) look like the best options. The car will still drive fine for a long time, none of the rust is structural or mechanical, I'm just worried about it reaching the fuel tank on the left side and it compromising the door seals eventually (it's creeping really fast on the underside), which will make things much worse very quickly. One other thing I've had suggested to me is to sell the car now while it still has some value and get another car, although I'm not a huge fan of that option.






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I think you're definitely past the point of any sort of reasonable repair. As you said, it would cost more than the car is worth, even after the repair.

No need to worry about the fuel tank. It's plastic and located under the driver and passenger seats, otherwise known as the limited edition ejection seat option. Maybe you mean the fuel filler area.

Check out some Youtube videos about Fluid Film or PB Blaster Surface Protect. Both are highly reviewed. If you have a friend (or friendly mechanic) with a car lift, get your Fit up in the air, pull off the wheels, and clean everything as well as you can. Where you have panel perforation, try to remove as much of the accumulated crap (dirt, rust, etc) from inside the panels. An air compressor and pressure washer will be your friend. Once you're clean(ish) and dry, start applying your product of choice.

If you don't have access to a lift, you can apply Fluid Film or similar to the undercarriage while the car is on jack stands but it's a messy pain in the butt and you will ruin a set of clothes. Well, not ruined so much as well-waterproofed. Definitely wear eye protection and probably a mask as well.

In the areas where you have full perforation of the panel, make sure that you get the product on both the outside and the inside of the panel.

If you can find a lift that will would also be an ideal time to really check out the rest of the undercarriage, as it's unlikely that you've reached this stage of exterior rust without significant corrosion of the floor pan, suspension components, etc.

I hope you can keep it going. Good luck.

 

Thanks for the advice. Yeah, it's not looking good. I get it serviced twice a year for the usual (fluids change, brakes check etc.), and I've had them inspect the rust's progress on the structural and mechanical components each time. The rear exhaust heatshield was fully rusted away and falling off, so that was removed. Everything else is in good condition, which makes this such a heartbreak.

 

@Drew21 @Frenzal Excellent thread, gentlemen. One of the best that I have read.

I have never heard of Fluid Film. It sounds like miraculous stuff. I was thinking of applying it to my axles as a preventative against rust, but, according to their site, it may not be safe on or near the axle boots.

"Care should be taken around non oil resistant rubber goods. May cause swelling. FLUID FILM® may soften some vehicle undercoatings. This includes undercoating type paints. Check with dealer/manufacturer for compatibility."

I was thinking that the OP should be cautious about other rubber parts around the car when applying Fluid Film. Please comment.

 

Mister Coffee asks an interesting question. In a general sense, I suspect that most of the rubber used on a car undercarriage is oil resistant because cars are oily beasts. I think we all hope that CV boots are made of oil resistant rubber as they hold in the grease lubricating our CV joints.

In my head I thought that I used Fluid Film on our cars, but when I just checked my records it turns out that I used Blaster Surface Shield (note that I mistakenly called it "Surface Protect" previously). I do remember reading and watching videos about Fluid Film, Surface Shield, and Woolwax prior to treating our cars. Knowing myself, I most likely used Surface Shield because it was the cheapest and I could get it locally (Home Depot).

Anyway, I don't remember being concerned about the rubber parts under the car (e.g., CV boots). I didn't intentionally spray them, but I also didn't worry about a little overspray. Was this laziness or did I read that I didn't need to worry? I honestly can't remember, but I haven't observed any paint, rubber, or plastic degradation in the areas I sprayed over two winters ago.

To confirm my assumptions (or start a dizzying cycle of existential regret for past indiscretions), I referred to the FAQ section on the Blaster website (https://support.blasterproducts.com/...ns/44000319884) where I found several relevant answers.
1) "While Blaster Surface Shield® is great for steel, it won’t harm plastic, rubber, glass or wiring."
2) "Blaster Surface Shield® is safe on all materials that can be found on a vehicle's undercarriage."
3) "No, it will not harm painted surfaces."

So, I'm pretty comfortable that Blaster Surface Shield is safe under the car. As I said before, it also waterproofed my jacket and made me smell like a wet sheep. Good times. Since I haven't personally used the other products I'll let someone else dig further on those.

 

I just sold my 2005 Accord, waiting for my new car next month, and I don't know what to do for rustproofing...

In the past, my trusted mechanics did some rustproofing using grease. Worked well for me on 2 car: 2005 Accord and 2000 Civic. Sold the Civic without any rust in 2019. Just sold the Accord with some rust, but minimal (3 rust spots - both rear fenders, not on the same place and a little bit on the driver's door).
Now my mechanics doesn't do rustproofing anymore, so I have to find something else.

For sure, I won't do undercoating like this:

I'm not really incline to do the dealer rust proofing using a wax like product. That can trap moisture in, and you have to go back every year to get it checked (and by experience, the dealer won't add any more even if you go every year to get it checked).

So, what is left is:
- Oil rust proofing from a national chain (have to get every year);
- Grease rust proofing from a family owned shop (have to go back every 3 years, which I find a bit odd - if I go this route, I might go back every year just to be sure they add some if needed).

One thing I am sure, is that here in Canada, you need rust proofing as otherwise, your car will rust badly in 5-10 years.

 

Ah, that looks familiar; my Chevy Cobalt looked like that from wheelwell to wheelwell, on both sides of the car. I finally had to retire the car for fears of losing the rear axle at the first inopportune bump!

The Fits do tend to rust quickly in those wheelwell arches. I hope to delay that on mine with frequent applications of Surface Shield. Hopefully it is warm and dry this weekend and I can power wash that area and let it dry, and then spray it with film. And yeah, it's got a peculiar smell.