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Mazda 3 - Rust in Mazda 3 - catsdad

My wife’s 2012 Mazda 3 has had light rust in some of the seams under the bonnet for a couple of years. This has been contained by Hammerite.

This week it was MOTd by our indie and he gave an advisory for rear subframe rust (“rear subframe is corroded in places”). I am old enough to remember rust and welding being a regular occurrence in the 70’s but this is our first modern car with an issue.

Anyway, discussing with the indie, he says the subframe rust is not very serious and he can treat it with Schutz for an hour and a half labour and £30 materials. £120 in all.

I am going ahead as it will mean the advisory will go at the next MOT. Given we have had two rust issues it’s probably not the keeper I thought was. Or do many nine year old cars now have rust if you look for it?

My faith in Japanese cars is being dented by this coming on top of my previous 2012 Civic suffering from the oil consumption issue.

Mazda 3 - Rust in Mazda 3 - groaver

We had a 2011 Mazda 2. Rust bubbles all over the roof discovered when trading in.

We had a 2014 Mazda 6. Rust appeared in the boot at the seams.

I have a 2020 MX-5 (fingers crossed!)

I don't think Mazdas are the best in terms of their rust-proofing although Subaru probably aren't too far behind.

Great drivers' cars though.

Edited by groaver on 08/10/2021 at 11:03

Mazda 3 - Rust in Mazda 3 - Manatee

I have a 2020 MX-5 (fingers crossed!)

.

Crossing fingers is the cheap option but probably ineffective. Seriously, treat the MX-5 now. Many are relatively low miles so are killed by rust, or fortunes are spent fixing them.

I had mine (2017) treated when I bought it at 6 months old, by The MX-5 Restorer at Pevensey in East Sussex. They know where to put the jollop, they do rust repairs every day, As it was like new underneath they used clear wax rather than the black stuff so it can be seen to be corrosion-free. I intend to keep it anyway but given the reputation of MX-5's for rust, I think it would be a plus were I to sell privately too.

Edited by Manatee on 08/10/2021 at 17:52

Mazda 3 - Rust in Mazda 3 - groaver

Thanks for the advice, Manatee.

Out of interest, what did it cost to treat?

Mazda 3 - Rust in Mazda 3 - Manatee

Thanks for the advice, Manatee.

Out of interest, what did it cost to treat?

Under £400, maybe £380, in November 2017. From memory it was a bit under the estimate because it didn't need much cleaning or any rust conversion. For me, money well spent. I intend to keep the car for as long as I can get in and out of it.

Mazda 3 - Rust in Mazda 3 - groaver

Thanks for the advice, Manatee.

Out of interest, what did it cost to treat?

Under £400, maybe £380, in November 2017. From memory it was a bit under the estimate because it didn't need much cleaning or any rust conversion. For me, money well spent. I intend to keep the car for as long as I can get in and out of it.

Thanks for the tip. :)

Mazda 3 - Rust in Mazda 3 - groaver

Thanks for the advice, Manatee.

Out of interest, what did it cost to treat?

Under £400, maybe £380, in November 2017. From memory it was a bit under the estimate because it didn't need much cleaning or any rust conversion. For me, money well spent. I intend to keep the car for as long as I can get in and out of it.

Undersealing process of the MX-5 started today.

Company send pics daily of the works progressing.

For a car that hasn't been out in salted roads with 4k on the clock, the rust on suspension arms and various other structures was a bit unnerving.

I was warned that Japanese cars are the worst that they treat.

I was also told that a new Toyota Yaris GR with 5 miles on the clock was showing some signs of rust when they treated it.

Mr Miyagi was half right: Wax on!

Mazda 3 - Rust in Mazda 3 - Engineer Andy

Thanks for the advice, Manatee.

Out of interest, what did it cost to treat?

Under £400, maybe £380, in November 2017. From memory it was a bit under the estimate because it didn't need much cleaning or any rust conversion. For me, money well spent. I intend to keep the car for as long as I can get in and out of it.

Undersealing process of the MX-5 started today.

Company send pics daily of the works progressing.

For a car that hasn't been out in salted roads with 4k on the clock, the rust on suspension arms and various other structures was a bit unnerving.

I was warned that Japanese cars are the worst that they treat.

I was also told that a new Toyota Yaris GR with 5 miles on the clock was showing some signs of rust when they treated it.

Mr Miyagi was half right: Wax on!

Maybe I've just been lucky (though I do live in the drier E.Anglia [just] area and nowhere near the sea) with my nearly 16yo Mazda3, but whenever I get the report back at the annual service, they always say how well the underbody is faring. Mine's got a bit of rust spots on the wheel arches, but nothing to write home about as yet.

Your 'wax on' comment reminds me - I still have a full car waxing kit amongst all the car valleting stuff (the good AutoGlym stuff) I bought years ago (same time as I bought the car) and never used it!

Mazda 3 - Rust in Mazda 3 - groaver

Your 'wax on' comment reminds me - I still have a full car waxing kit amongst all the car valleting stuff (the good AutoGlym stuff) I bought years ago (same time as I bought the car) and never used it!

It could still be usable.

I find polishing and waxing a car rewarding.

Mazda 3 - Rust in Mazda 3 - Engineer Andy

Your 'wax on' comment reminds me - I still have a full car waxing kit amongst all the car valleting stuff (the good AutoGlym stuff) I bought years ago (same time as I bought the car) and never used it!

It could still be usable.

I find polishing and waxing a car rewarding.

Perhaps I can learn karate as a result?! I already know kung-fu, after watching The Matrix. :-)

Mazda 3 - Rust in Mazda 3 - groaver

Perhaps I can learn karate as a result?! I already know kung-fu, after watching The Matrix. :-)

Is that Kung-fu?

No, he's only had the one drink.

I'll get my coat...

Mazda 3 - Rust in Mazda 3 - Engineer Andy

Perhaps I can learn karate as a result?! I already know kung-fu, after watching The Matrix. :-)

Is that Kung-fu?

No, he's only had the one drink.

I'll get my coat...

We've already gone and it's only Wednesday! :-)

Good to still see the banter on the site.

Mazda 3 - Rust in Mazda 3 - MVP

When I took my 03 Forester in for an MOT this year I asked the tester if I should be thinking about getting rid as the car was 18 years old.

He said there was some light surface rust on the sub frame but nothing to worry about. He said if i bought a new car it probably wouldn't last as long as the Forester will.

I have never done any rustproofing, just jet washed under the arches etc each spring.

Mazda 3 - Rust in Mazda 3 - madf

Our 2003 Yaris lost paint along inner sills so I Dinitrolled them all.

The rear subframe is as new- Dinitrol and Waxoil

ALL cars rust - the average life of a car in the UK is c 12 years.

If you want longevity, look after the bodywork underneath.

Mazda 3 - Rust in Mazda 3 - Grenache

I have a 2012 Mazda 6, and the rear subframe components were rusty when the car was delivered brand new. Mazda's customer services were completely unhelpful, and it was only when I threatened to reject the car that the dealer arranged for a body shop to clean and coat the rusty spots. However in the intervening years the car has developed a number of rusty spots underneath, probably not helped by a few salty winters. I've not had an advisory on that, yet.

Mazda 3 - Rust in Mazda 3 - Andrew-T

ALL cars rust - the average life of a car in the UK is c 12 years. If you want longevity, look after the bodywork underneath.

In absolute terms, yes, all cars rust. But my Pugs 207 (2008) and 306 (1994) have had one trivial advisory each for surface corrosion, which have not reappeared on later tests, without any treatment.

So some makers found effective methods of rust prevention many years ago. Others have found ways to cut corners in that treatment, perhaps with the results you describe.

Mazda 3 - Rust in Mazda 3 - Engineer Andy

Mazda are, I think slowly learning their lesson on rust-proofing, with each generation of their models being a decent improvement on that score from the previous one.

I would also point out that - admitedly it's an anecdotal one from both my own personal experience owning a late 2005-build Mazda3 and of others, both here and on the UK Mazda3 owners' forum site - more of the problems appear to be with cars made in the first year after the model was changed, which means they do make improvements to both the design and manufacturing process as they go.

Mine has a few small rust spots in the most common place - the wheel arches, but otherwise is fine aside from a couple of bonnet stone chips*, which themselves have not go that bad despite being several years old. My dealership has even commented at how well the underbody area has faired generally. Never had even an advisory on an MOT for rust related issues.

Most the gen-3 (2014-19) rust issues I read appeared to pop up in the early cars, with very few reported on the owners' forum generally and even fewer for 2015+ build examples. Hopefully they have now resolved the 'problems'.

* thin car panelling and paint jobs are a common theme thes days, not just for certain Oriental makes, because it's an easy way for them to save weight. Nice work for the likes of Chips Away & Co though.

Mazda 3 - Rust in Mazda 3 - madf

Anyone with any Mercedes built between c 1995 and 2005 will have a detailed personal knowledge of rust from after the car was about 3 years old.

Mazda 3 - Rust in Mazda 3 - SLO76
The big downside to Mazda ownership is rust despite big steps forward with the post facelift 3 and Mk II 6 but the Mk III MX5 still crumbles like it’s the 1970’s over again. It seems examples which hail from coastal areas, particularly in colder Scottish climes are more inclined to rot. If buying a used example you do need to get it on ramps for a good look underneath or be limber enough to do it without. I still rate petrol Mazda’s, I see them as better looking and driving alternatives to Toyota and Honda but they do rust more so some preservation is worthwhile before the car rots too badly. It needs to be bone dry before application and not too far gone or it’s not worth doing.
Mazda 3 - Rust in Mazda 3 - Engineer Andy

It'll be interesting to see how the latest Mazdas fair, as they appear to have been a significant improvement in the fit and finish quality, as I believe they intend to go 'up market'. Hopefully this will prove to extend to the rust proofing and other niggly issues certain models or ones with certain engines have had over the years.

To be fair with the MX-5 mkIII, it was around for nigh on 10 years, which is a long time for a model to be out, just around the time when money was tight for them during the economic woes of 2008 and the subsequent divporce from Ford.

Have you heard of any issues with later MkIIIs or the mkIV from 2015 onwards? Most of the issues for the latest Mazda3 on the owners' forum tend to be to do with (as is the case with many modern cars) faulty electronics on one of the many gizmos they now have.

One thing also that was mentioned was people treating the underbody when they buy new, but I seem to remember being told that it isn't always possible for all areas because some need to be inspected for the service/MOT and occasionally adjusted or opened for maintenance. Does it affect the warranty?

I must admit thinking about getting it done for my next car (given I tend to keep mine a long time) - if it's worth it.

Mazda 3 - Rust in Mazda 3 - SLO76
Been a while since I’ve inspected an MX5, Mk III or otherwise. Certainly the early examples I looked at or sold over the years were mostly showing rust that they shouldn’t have at the age they were. A friend does have a very tidy 10yr old example which looks completely rust free on top, I may take a wee peek under it at some point. I hold onto hope that the new model won’t suffer this but again I kinda hoped this with the Mk III.
Mazda 3 - Rust in Mazda 3 - Manatee
A friend does have a very tidy 10yr old example which looks completely rust free on top, I may take a wee peek under it at some point. I hold onto hope that the new model won’t suffer this but again I kinda hoped this with the Mk III.

A friend bought a 2012 Sport Black a couple of years ago, rust-free despite being from Torquay! But he had looked at at least a couple that were completely brown underneath.

So far the Mk4 seems OK, there are large areas with no obvious sign of special protection but they don't seem to be rusting there - the oldest cars are MY 2015. But as we know, the Mk2's rusted from the inside out, in the sills, rear arches and the 'laminated' front chassis rails. I decided I'd get my retaliation in first and put it in for some protection. It was a bit under £400 I think, and certainly cheaper than typical rust repairs, although there is no guarantee that it will never rust.

I'm sure you're right about the importance of the car being dry before treatment. Any but a very new car will also need washing off and drying out. Despite this many "rustproofers" only want the car for a day. Just possible I suppose to do it properly if dried with a lot of heat but I wasn't convinced. The jollop is fairly tacky and smelly for a while as well and is probably better allowed to dry. The people I used wanted it for a week. I bought a return train ticket, left it on a Monday and picked it up on Saturday morning.

Mazda 3 - Rust in Mazda 3 - Big John

Anyway, discussing with the indie, he says the subframe rust is not very serious and he can treat it with Schutz for an hour and a half labour and £30 materials. £120 in all.

I am going ahead as it will mean the advisory will go at the next MOT.

Myself I wouldn't use underseal on a rusty surface - it can fester underneath and you can't see what's going on until it's too late. Of late for subframes/backplates/suspension and indeed exposed body metal I've been a great fan of Owatrol oil. Fantastic rust inhibitor and then protector. Paints or sprays on like clean engine oil and sets to a kind of resin finish and stays there even with lots of road spray etc. Doesn't fix the rust but stops it getting worse and you can easily keep an eye on it.

As an example I painted the badly rusting sump of Mrsbj's Fiat Panda about 5 years ago - still looking good. I've now also done the rear suspension in the same.

Edited by Big John on 08/10/2021 at 21:34

Mazda 3 - Rust in Mazda 3 - catsdad

I would agree that a converter like Owatrol is a good approach if I was doing it myself. I am under no illusions that what my garage is doing is, at best, only going to hold it for a year or two. However they use this Schutz stuff all the time and, having sought their advice, I will stick with it.
I will also check with him once he has wire brushed it and done the work as to how far the corrosion has gone. Even if he gives it a clean bill of health for now, no liquid or underseal will restore lost strength. Once rust is present I reckon it’s just a question of time before it comes back here or somewhere else in the car.

Mazda 3 - Rust in Mazda 3 - Big John

However they use this Schutz stuff all the time and, having sought their advice, I will stick with it.

It is possible to underseal well but preparation is all. It's where people just paint black goo over crispy rust that it really causes issues.

When I used to restore cars / weld etc years/ er decades ago I used to apply clean engine oil to exposed surfaces the day before applying Waxoyl underseal - if there were any rust "pits" left over they would end up with oil trapped between the underseal and the pit or seam etc. You would think it wouldn't apply but it somehow did but it was super messy. Back then I used a warm oil/waxoyl mix sprayed inside internal structure.

I revisited a car I restored in 1988 a few years ago and the rust proofing was holding up well 30 years later, the only rusty bit was the boot lid that was perfect at the time in 1988 so got overlooked re treatment. This car was a 1968 Moggy Minor that would have only been 20 years old when restored - most of the chassis that held the rear leaf springs, sill structure , rear inner wing/wing mounts lips/wheelarch, crossmember was all toast at the start. The eye of one leaf spring was hanging in mid air inside the boot!

Mazda 3 - Rust in Mazda 3 - ifekas

I am going ahead as it will mean the advisory will go at the next MOT. Given we have had two rust issues it’s probably not the keeper I thought was. Or do many nine year old cars now have rust if you look for it?

Funnily enough, I have been looking for a cheap(ish) small automatic car for a friend, and looking at the MoT history of cars for sale, loads of cars seem to have this issue.

Since I like KIA, I thought something like a KIA Venga, Rio or even Picanto might be good, but a number I had a look at that were 63 or 64 plates had MoT advisories for rear subframe rust and even rust on brake pipes despite the mileage being relatively low. There were quite a number of other makes that had similar MoT advisories, so KIA/Hyundai and Mazda aren't alone; though since I was trying to look for cars with a reliable autobox, the choice was much more restricted. The car that seemed to do best in my searches was the Vauxhall Agila auto, though perhaps that's because they may likely have been owned by an elderly lady and only driven five miles to Sainsbury's once a week ;-)

My 10 plate Ceed soldiers on and that model is also known for underbody rust; when it was about six years old it had a 'product improvement' where the dealership sprayed some black stuff on the underside; I'm not sure whether that would have slowed down the rusting after all that time, but since it didn't cost me anything...

Mazda 3 - Rust in Mazda 3 - John F

For many years I occasionally applied old engine oil with an old toothbrush to the springs and subframes of our Focus. It failed the MoT for rust the first time at 16yrs old and the next time at 18yrs old, both due to corrosion tracking under the 'protection' (ha!) on the sill area by the rear wheels. The subframes have also had an occasional coat of Hammerite. In December it will become of age at 21 yrs old, and might be allowed a drink of fresh 5W-30.

Mazda 3 - Rust in Mazda 3 - Big John

In December it will become of age at 21 yrs old, and might be allowed a drink of fresh 5W-30.

Steady - don't overdo it!!

Not a fan of using old engine oil, it can be acidic and eat into metal an do damage - depends on how hard a life it's had before. When applying you should avoid skin contact as it can be rather carcinogenic.

Saying that many moons ago my Dad's old mkII Cortina when near end of life due to rust was in perfect condition in the centre rearwards from the bellhousing tunnel due to the amount of oil mist that vented out of the engine breather and coated some chassis / body parts - yup vent to atmosphere back then! Oil was probably always fairly new due to the amount it was burning and having to be topped up by.

Re proper hammer finish Hammerite. Fab stuff - saved the boot vanishing on the same said Cortina but on exposed parts it could be prone to chipping. I was never as keen on Smoothrite.

Edited by Big John on 09/10/2021 at 19:16

Mazda 3 - Rust in Mazda 3 - Falkirk Bairn

My 1998 Mazda Xedos was mechanically almost perfect in my ownership of over 15 years.

Sold it in 2014 - I had had Chips Away rubbing down rear wings twice and trying to make it look better - rest of body was excellent, even the sills.

I sold it for £500 and the new owner did 20K in around a year. Engine blew for some reason - the rear suspension mountings were showing serious rust as well. If the end if the engine had not gone bang the rear suspension rust would have killed it .

Mazda 3 - Rust in Mazda 3 - catsdad

Just an update. The Mazda 3 subframe was treated this week. Before he did it I asked the mechanic to give the wider underside a check over for other future rust risks. I wanted to know if I should expect wider rust issues and get rid sooner rather than later.

I am pleased to say that he reckons it’s sound and there is nothing else to treat and no need to move it on. Even the subframe itself he says is typical of many cars of that age.

Looking at the treated frame he appears to have done a thorough job. It’s a thick and hardly pretty finish though. I suspect if I took it for an MOT elsewhere I’d get an advisory for inability to assess the frame due to the coating. Hopefully by going back next year to the guy who did it there will be no risk of that. It will need monitoring though as undersealing might conceal problems rather than solve them.

So, for now, the Mazda is back in the good books.

Mazda 3 - Rust in Mazda 3 - Xileno

Sounds a good job done by the garage and hopefully you will get plenty more years out of it.

Mazda 3 - Rust in Mazda 3 - John F

In December it will become of age at 21 yrs old, and might be allowed a drink of fresh 5W-30.

Steady - don't overdo it!!

Not a fan of using old engine oil, it can be acidic and eat into metal an do damage - depends on how hard a life it's had before.

In theory perhaps.....but I have never observed it 'eat into metal', even in our nearly 21yr old Focus. And my oil usually works hard and long before it gets changed! Perhaps it was noticed decades ago using ancient oil full of blow-by acidic contaminants.

When applying you should avoid skin contact as it can be rather carcinogenic.

Only if prolonged contact - i.e. many years unprotected unwashed exposure. Not a problem for the occasional amateur mechanic.

But the best thing is protection from new, e.g. my Ziebarted 1980 TR7, which has outlasted more than one generation of MX5s. Or better still, an aluminium car, e.g. my 16yr old Audi A8 - no corrosion anywhere.

Mazda 3 - Rust in Mazda 3 - madf

" Or better still, an aluminium car,"

NOT a Jaguar XJ6 with aluminium body rivetted with STEEL rivets.. Guess what happens? - corrosion as any A level chemist would know.

Mazda 3 - Rust in Mazda 3 - John F

" Or better still, an aluminium car,"

NOT a Jaguar XJ6 with aluminium body rivetted with STEEL rivets.. Guess what happens? - corrosion as any A level chemist would know.

Yes, I did wonder about that when I was looking for my 'forever' retirement car nearly eight years ago - Jaguar was on the shortlist. I believe Mercedes also mix and match alloy and steel. Not a patch on Audi's superlative pioneering aluminium 'space frame'. Have any owners of 15-20yr old alum-Jags out there had to have remedial work done?

Mazda 3 - Rust in Mazda 3 - Engineer Andy

" Or better still, an aluminium car,"

NOT a Jaguar XJ6 with aluminium body rivetted with STEEL rivets.. Guess what happens? - corrosion as any A level chemist would know.

The same reason why you don't mix and match certain pipe materials (and in certain orders) in plumbing.

Yes, I did wonder about that when I was looking for my 'forever' retirement car nearly eight years ago - Jaguar was on the shortlist. I believe Mercedes also mix and match alloy and steel. Not a patch on Audi's superlative pioneering aluminium 'space frame'. Have any owners of 15-20yr old alum-Jags out there had to have remedial work done?

Not this issue, but a former colleague of mine did own a Jag which caught fire and distintegrated in a matter of minutes because of the aluminium and magnesium parts.

Mazda 3 - Rust in Mazda 3 - Big John

In theory perhaps.....but I have never observed it 'eat into metal', even in our nearly 21yr old Focus. And my oil usually works hard and long before it gets changed! Perhaps it was noticed decades ago using ancient oil full of blow-by acidic contaminants.

Possibly - the worst I saw was on a rescued engine from an old Morris Bullnose that had been "stored" on its side for some time. The part of the crank submerged in stinky oil was in a really bad way. A shame as the rest wasn't too bad.

My Dad had a mkII Cortina owned from a couple of years old until the late 70's. The only bits not being ravaged by rust by then were the parts being "oiled" by the leaky old engine with an oil vent pipe that vented to atmosphere near the bellhousing.

Back in the day to rust proof I used clean engine oil mixed with Waxoyl splattered inside chassis/sills etc.Oil is useful stuff as it soaks into things.

Edited by Big John on 23/11/2021 at 20:24

Mazda 3 - Rust in Mazda 3 - Bolt

I only had one Civic as an oil burner and the 2008 has no rust or burns oil though its the so called slow 1342 engine but its quiet and economical so will keep it for a while

Talking of rust I have seen younger german cars with rust on boot/tailgates and some on the door bottoms so its not that bad on that age imo