I was a motor mechanic in the 1970s - doing my apprenticeship with a Vauxhall main dealer. At the time, Vauxhall were turning around their previous poor record on rust by undersealing all their new cars at the factory.
Not all manufacturers back then did underseal their cars of course, but changing jobs a number of times, and working on a wide variety of British and foreign makes for the rest of the 70s, I witnessed many taking this up.
I moved away from the car trade in 1980, and never really kept track of what manufacturers were doing in this respect. Certainly the cars I owned during the next twenty-odd years did seem to have undersealing, but then perhaps that was due to the make of cars I bought in that period.
When I joined the OC in 2016, I was astounded that there were so many posts on the forum about Mazda’s poor record on rust. I mistakenly (as I have since learned) assumed that all car manufacturers had taken up undersealing their cars at the factory, especially as cars these days do seem to last longer than they did when I was a mechanic all those years ago. But no, it appears Mazda’s policy is to leave it to the new-car purchaser to do this, as some countries do not have to contend with rust issues like we do in Britain - it seems to depend on each individual country’s climate, and how, if needed, each country deals with icy roads. Mazda’s policy seems to be why spend money undersealing their cars if, in many parts of the world, it is not necessary.
So yes, if you intend to keep a new Mazda for a long time, MX-5 or whatever, it would be a good idea to have it properly undersealed - around £500.00 seems to be the going rate for a thorough job. If on the other hand, you only plan on keeping it for (say) five years, it could well seem to be a waste of money, because you are not going to be the owner when rust rears its ugly head.
Ironically, the worst car I ever had, in terms of rust, was a 1985 Vauxhall Astra that had started to dissolve significantly by the early 90’s!
Regarding the original question, if you are going to keep the MX5 for a number of years, then getting it rustproofed seems like a good idea. Doing it for the 4th or 5th owner, if you’re not keeping it, would probably only be of help to them if the 2nd & 3rd owners keep the rustproofing in good order.
My plan is to keep mine running around 7 years and 120,000 miles.
At that point I would expect any major body, engine, or electronics failure to effectively write off the car.
Electronics is the main recent difference.
If you run the car for 15 years and only 30,000 miles then on older cars rust was the main consideration for failure - but now, what are you doing to protect the infotainment and other electronics from failure?
…going back to my earlier post regarding our Mk2.5 and getting the sills done. It was not until I dug out the pics I took that I realised that we had the sill repair done at the 7 year mark, (I had thought it was much later than that). The pictures I took show how badly the sills had corroded in just 7 years. They must have been “well on their way” after just a few years from new!
Yeah I’m a biker too & always give my bike a good coating of ACF-50 before winter.
First time owner of MX5-RF so no experience of corrosion to date, but can’t see it doing any harm having a good coating of ACF-50 underneath. I’m planning to get mine up on a ramp and giving the underside a going over
My 2.5 was bubbling in the quarter panels at 4 years old… one of the reasons for my caution (paranoia) with respect to MX-5 rot!
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I was surprised to read that IanH’s mk.2.5 was showing signs of rust bubbling at only four years old. Perhaps the fact that he lives in Scotland had something to do with that. The winters are longer and harder up there of course, so the use of salt is bound to be more widespread.
Spending an extra £500 or thereabouts on rust-proofing a new Mazda, to probably only benefit a subsequent owner a bit further down the line, does display a certain altruistic tendency I suppose, but I for one am glad such people exist. Not being a great fan of the shape of the ND, or for that matter, the Active Bonnet thingy, when my wife and I begin our search for a replacement for our current 2008 Sport in the next year or so, we will be looking for something like a mk.3.5 (NC2) of around the 2012 / 2013 vintage, so finding one that has been perhaps cherished and cosseted will be an important concern.
My opinion Phlissy is along the lines of what some others have said on here -
If you know that you'll only be keeping it for 3 years, I wouldn't bother.
However if it's likely that you'll be keeping it for longer than that (I'd say 5 years+) then definitely get it done.
Mine was bought new & I was already aware of the reputation for rust when I decided to treat myself to an MX-5; I usually keep my cars for between 7 & 9 years so in my case there was no decision to make - it went in for rustproofing very shortly after I took delivery. 7 years later, it's obvious that money was well spent.
Ref a point raised earlier - is the location of the car a factor here? I’m a northern lad & can testify that southern winters are a hell of a lot milder. In “sunny” Surrey I rarely see the gritters out, whereas in “grim up north” Middlesbrough they were a regular feature over the winter months.
…not sure location is relevant. When we had our sills done they did not look too bad from the outside, just a couple of “bubbles”. It was only when the “skin” was peeled back that the “full horror” of the corrosion became evident.
Our Mk 2.5 had not been used in the winter, so technically I don’t think our corrosion had been caused by “salt”. Seemed to be more of an issue of condensation behind the outer panels which had not been treated causing the problem. If I knew how I would paste the pics I took after the car was a “mere” 7 years old. They must have been well on their way after about 4 years or so?
I can’t see what all the fuss is about to be honest. Compared to anything ever produced in this country, Mazda are a shining beacon of excellence. Plus they are put together properly & you know you have a more than fair chance of making it home under your own steam!! Yes, I did grow up with BL produce & turn of the century Fords unfortunately.
Even the youngest of the NB’s are now around 15 years old so of course will have some rust. Seems like some folk may have their expectations set a little high.
That’s right - if the car’s parked outside, condensation will certainly occur - particularly during the colder months, within the body shell cavities causing “inside out” corrosion if the cavities haven’t been adequately protected.
So if a car isn’t used during winter but left parked outdoors, "inside out"corrosion will still occur if the internal rustproofing’s below par regardless of the amount of salt on the roads.
Agreed - Sheffield’s roads (despite being some way south of Middlesbrough) seem to be gritted on an almost daily basis between late October & at least mid April!
While Mazda does not necessarily cover itself in glory in this area, it is not exactly unique. If this was a Ford KA forum for instance there would be no difference. 2005 Rover 200’s and MG’s would feature strongly and so on. Individual cases are also never representative of the whole as there can be a whole world of issues that have caused specific cars to rust early. From debris on the road damaging wheel arch protection, how, where and how long it is parked, even down to the way a car has been jacked up.
It is interesting to note that people suggest getting secondary rust protection that needs maintaining every 3 years, while moaning that factory protection is not good enough to last 10 or more.
Rusting is of course not unique to Mazda. Though the rusting we are talking about is the rusting that falls under Suspension–> Prescribed areas, and Seatbelts and Supplementary Restraint Systems–> Seat belts → Prescribed areas.
You pick 2 other cars that are thought to be comparable, in terms of rusting: the Ford Ka, a cheaply built budget car, the 2005 Rover 25 (200 was no longer made by then, the 25 wasa revised version), a car built in the last year of a company that went bankrupt.
Newer test data is now available, but now companies have latched on to use Panther analysis to sell this data in a more accessible format. The most accessible recent data is 2016 test data through the Telegraph’s Honestjohn:
Where all the model data is compared against others of the same year.
Overall, better than other 2005 cars, but generally worse than other 2005 cars in those rusting areas.
2005 Ford Ka; grim reading, but not a surprise, because near enough everyone left appears to be verging on a rust bucket. Don’t think Ford are losing sleep. It was a cheap disposable car.
2005 Overall, the 2005 Rover 25 is a bit worse than the 2005 MX5, for pass rate, at 57% versus 67% (strangely, the MG ZR is worse than the Rover version, at 51%, odd that, considering they are basically the same car). But when it comes to the comparable areas, its a bit better than the MX5. Some oddities with the MG version. Now, its also worth reflecting that the MX5 is a two seat convertible; it is a less practical car than a hatchback. Its less likely to be used on a daily basis. Its more likely to be used as a hobby car. Its more likely that the owner might consider themselves an enthusiast. All that feedbacks to a general expectation that a MX5 enjoys a better level of upkeep than most other 2005 cars. Rusting is one area that most owners find difficult to avoid, because on the MX5, its from the inside out, not outside in (ie. underseal is a red herring; underseal or lack of, is NOT causing rusting failures)
But maybe rusting on the MX5 is just something you should expect with a roadster, because it has super complex internal structures, through which water drains, creating rust traps? BMW Z4 data indicates that for 2004, overall fail rates are worse than for the MX5, but what they are not failing on is rust:
We should not be comparing the MX5 to cheap disposable shopping cars (though the Peruoda Kelisa, which might have been the cheapest of the cheap, does ok), but to its peers, to eliminate variances caused by how the cars are used (careless owners etc). Needs a deeper analysis based on the available data.
