Anti rust treatment on the MK4

[teralek]

As anyone applied anti rust treatment on the MK4 here? I'm thinking about Dynax UC
Is this safe if the car is still under warranty? I believe this is safe to apply as it is a clear coat and doesn't interfere with normal service, just wondering if anyone did this before to a MK4 Jazz.

[Downsizer]

I don’t think this is needed with modern manufacturing techniques.

[teralek]

why is that? If there are metal parts exposed under the chassis there will certainly be a build-up of rust over the years enhanced by salty roads.

[Jazzik]

Some time ago, I happened to come across the following information regarding rust prevention for the car that will replace our Jazz at the end of November:
"The body of the BYD Dolphin G undergoes electrochemical galvanization (electro-galvanization), which is the industry standard for modern cars to prevent the formation of rust."

[Kremmen]

But the question is not about your beloved BYD, this is a Honda forum

[emp]

I have seen videos on youtube of them doing such an anti-rust treatment. It is quite a lot of work so it is not cheap.

Gemini AI says: "Honda uses double-sided electro-galvanized sheet steel and zinc-nickel/zinc coatings across body panels for factory corrosion protection.  During manufacturing, Honda applies a multi-stage immersion dip (electro-deposition or "E-coat"), seam sealers along joined sheet metal edges, and targeted underbody PVC stone-chip guards. European Honda Jazz models also carry a standard 12-year anti-perforation warranty against internal structural rust."

But it also says under certain circumstance (salty road conditions etc) your Dynax UC treatment is highly recommended. Best ask gemini about it yourself.

[d2d4j]

Hi

If you have an older car, when was the last time it needed body patching for rust

I have not read any apart from the very early model say 2003 which needed work by petrol filler area

I think the real rust is to components fitted after factory body treatments such as subframes brake pipes etc… which do not have same protection

Many thanks

John

[Jazzik]

But the question is not about your beloved BYD, this is a Honda forum

It's indeed NOT about my beloved(?) BYD but about ehhh...

"The body of the BYD Dolphin G undergoes electrochemical galvanization (electro-galvanization), which is the industry standard for modern cars to prevent the formation of rust."

Of course, two questions remain open: Do you consider the Jazz a modern car, and does Honda operate according to industry standards?
In my opinion, both questions should be answered in the affirmative.

[coldstart]

Of course, two questions remain open: Do you consider the Jazz a modern car, and does Honda operate according to industry standards?
In my opinion, both questions should be answered in the affirmative.

The MK4 Jazz definitely is a modern car!
As for your second question: I am quite certain, that Honda doesn't operate "according to industry standards" but according to its own standards (imho superior to "industry standard") and has quite a track record of providing very reliable and durable cars!    (something, your "beloved" BYD has yet some 30 something years in front of itself to prove, wether it can live up to Honda standards)

I'm still seeing MK2 Jazzes on the road regularly, which now are well beyond 10 years old, so Honda seem to have something going for them quality-wise.

[Jazzik]

Wow... I thought I was responding to the question whether or not to apply an anti-rust treatment.
Now, it looks like some people are reacting as if my better half should be jealous of a little Chinesecar.

Maybe re-read my first response « Reply #3 on: October 27, 2026, 06:56:00 PM » carefully...
And also my second response « Reply #7 on: Today at 10:47:15 AM » (especially the last sentence!).

[coldstart]

Wow... I thought I was responding to the question whether or not to apply an anti-rust treatment.
Now, it looks like some people are reacting as if my better half should be jealous of a little Chinesecar.

You were! - However, in a somewhat "proselytising" way
And.... imho you should definetely worry about your wife's feelings! (not only about your choice of car!)

Moreover: This is a Honda forum! - So be prepared to meet with resistance while "peddling" chinese cars onto the unsuspecting public

In German we have a saying: "Reisende soll man nicht aufhalten" which roughly translates into "no good will come from trying to stop travellers from moving on".

Please, do us the honour and do move on to "greener pastures" of your choice and leave us to our restricted (Honda) view of the "world" - thank you!
My theory about missonaries goes somewhat like they are themselves insecure and think: The more people I can convince about my belief the truer it must be  - hey: I'm a Honda missonary myself

I wish you all the best in BYD-world!  (and thank you for all your insightfull contributions while still in the Honda-corner!)

@teralek: I'm extremely sorry about getting so far off-topic! I will refrain from further interference in this thread as I have absolutely nothing constructive to contribute about anti-rust treatment.

[Lord Voltermore]

Rust proofing  is a personal choice . Personally I wouldnt bother on a newish car  , but  DIY spraying with rattle cans of Dynax might have some benefit and reasonably cost effective.

IMO (with little actual experience or research)  rustproofing comes in 3 basic forms. 1) Thick bitumin type underseal coating. Water can get behind which can make rusting worse.   2) Paint  coating.   3) a waxy  oily coating which can be washed off or melts in hot weather   

Far from increasing the value of your car  Non  standard thick underseal or painted areas  is a red flag for many used car buyers (and MOT testers) who wonder what it might be hiding.   .  A clear waxy coating  (which like dynax can be removed with solvents such as white spirit), is less obtrusive  but may need periodic retreatment to have any long term benefit .

I would trust to the advanced galvanistic metal priming of modern cars (although Honda have a better reputation for mechanicals than bodywork)   Just treat any  chips and rust spots as soon as you find any.  Hose off thick mud, or road salt from time to time.  Beware of pressure washers.
The car is quite likely to last 10 years  anyway  before rusting becomes an issue for you or potential buyers.  Thereafter buyers might pay a few quid more on top of its low value for a particularly  rust free example. But was it worth the investment in time and money, and will you be the one to benefit?.   Its nice to think your car might eventually appear at historic classic car rallies, but only you know if you will get pleasure from keeping it in pristine condition.  And most older cars ,even rust free examples, end up in the crusher.

Bear in mind that some car manufacturers deliberately chose not to paint certain  cast iron suspension parts. Some metals do not  take primer or paint very well .The  surface rust may be unsightly but is quite effective protection  from any further  corrosion.

The paint on my platinum white 2021 car did chip quite easily.   I find the premium sunlight white pearl on my 2024 car much more durable. I think it has extra coats of paint  which  also makes the  panels feel more solid and less flexible.

[zdan]

I find rust proofing heavily dependent on what are your long-terms plans with the car.

- Are you gonna keep it for <10years? Forget about it. Money lost.
- More that 10 years? Could be an option.

[teralek]

Hi

If you have an older car, when was the last time it needed body patching for rust

I have not read any apart from the very early model say 2003 which needed work by petrol filler area

I think the real rust is to components fitted after factory body treatments such as subframes brake pipes etc… which do not have same protection

Many thanks

John

Before I had a 2010 Civic and I live in Edinburgh where salt roads in winter is the norm. I had plenty of rust advisories in the MOTs lately before I sold it in September (nothing major but getting worse).

Here's what the last MOT pointed on that car:

"Nearside Front Coil spring corroded (5.3.1 (b) (i))
Offside Rear Coil spring corroded (5.3.1 (b) (i))
Nearside Rear Coil spring corroded (5.3.1 (b) (i))
Rear axle corroded"

I could also hear a bit of a grinding noise on the wheels if I left the car for more than a day parked.

 So I don't think this problem went away exactly. Especially on exposed metal under the chassis, there are some. My plan is to keep the car for at least as long as my last (16+) years, I think I will go for Dynax UC as prevention for long term. If I wanted to keep the car for a max of 12 years I probably wouldn't worry, but that's not the case. I don't want the same to happen

[teralek]

I'm still seeing MK2 Jazzes on the road regularly, which now are well beyond 10 years old, so Honda seem to have something going for them quality-wise.

The MK2 is an awesome car. I had one from 2008 until 2021. Zero problems and zero rust. But this car was in Portugal with zero salt on roads and much dryer weather...