There have been quite a few posts recently, answering queries about the purchase of MX-5s, regarding the rust problem on older models.
It has been suggested by more than one member, that whatever car one buys, they should have in underbody sealed to protect it. Surely MX-5s, as with other cars these days, are underbody sealed from the factory - the two that I have owned seem to have been (a 2008 and a 2011), so why should it be necessary to have it done again?
Mazda view their vehicles as disposable commodities, they are in the business of selling cars. Therefore they don’t go overboard in protecting them from decay as they’d quite like you to buy another one after a certain period of time.
Many enthusiasts however become quite attached to their vehicles, which do after all represent a considerable expense when new. To increase anti rust protection over factory standard ensures a longer vehicle life and a better residual value for the owner, which perhaps isn’t good news for Mazda but is certainly good news for the MX5 enthusiast.
if you get a chance to look underneath a standard MX-5 you will see large areas with no underseal protection whatsoever. It’s ok when new, they’ll last a few years, but eventually will inevitably fall foul of the tin worm. I have added extra protection to my ND even though it’s unlikely I’ll keep her more than a couple of years, but nonetheless I’m sure her next owner will be pleased of it.
Thank you for your replies to my underbody protection query.
I have to admit to being rather shocked that car manufacturers can think they can get away with not protecting their products these days. I was a motor mechanic in the 70s and 80s, and rarely saw a new car that was unprotected in this way (in the dealerships I worked in anyway).
We’ve only recently bought a 2008 MX-5 as a second car, after missing the 2011 model my wife had as a company car so much this last summer. I will get our ‘new’ acquisition checked out as soon as possible.
as Peter-B said, many owners keep their 5s for years so will do everything to keep the dreaded rot away.
If your 5 is a keeper then extra protection is worth considering but every car is kept in a different way by the owner so it’s up to you.
example; 2 years ago I sold my early 1990 mk1 at 100000+ miles with only a little rust showing underneath.
my current Mk3 2006 with 4 previous owners, 90000+ miles has no apparent decay (& we have spent time underneath it servicing & replacing the starter motor)
As a former mechanic you may want to get your car up on a ramp and inspect it yourself Chris just for peace of mind.
Given that I use my car through winter I’ll be taking it HERE shortly for a full post winter underbody clean and wax. I dream of one day buying a one former keeper, summer use only, heated garage stored and cosseted motor, but until then the fight against corrosion goes on I’m afraid.
I think many new cars these days - those with galvanised bodyshells - probably don’t require extra underseal. A friend of mine has a 2009 VW Scirocco, ex-fleet car which he bought at 3 years old; it now has 80K on the clock & it’s still spotless underneath.
MX-5s on the other hand aren’t galvanised hence much more prone to rust. Additionally the quality of the factory undersealing work is poor - many critical areas e.g. subframe mounts had been missed on my 2012 NC2; as I planned to keep it for a number of years (I usually keep a car for between 7 & 9 years) I booked it in to be professionally treated shortly after taking delivery when the car was brand new. This despite it getting mainly summer use & always garaged - pleased to say that it’s still A1 underneath.
However if I’d only planned to keep the car for 4 or 5 years I probably wouldn’t have bothered.
As MX5 8ARY says above, this should certainly also be of benefit to whoever has the car after me!
As an individual who has spent around 4.5k in 4 years remetalling & preserving both our 5s, I take the pragmatic view that a new ND…is the similar price as a top of the range Mk2 Conran Platinum was way back…when fuel was less than 80p per litre.
In short, they are built both engineers and beancounters to a penny pinching price (read affordable) and always have been.
Every penny is a prisoner with them. Corners that can be cut are corners taken.
MX5s have never really rusted from the outside in, but from the inside out. Slapping a load of black bitumen all over the underside I’m sure makes the owner feel like they have done something, but I’m not sure it really achieves anything, especially on a newer car. On the older cars, the factory underseal can loosen a bit around the footwells. Mk1 boot floors were never undersealed by the factory, and nor are they generally considered a place of rusting. The money is better put towards cavity protection.
Cars rot from within because this is where the least paint is. Sometimes they seem to be designed to fail at about ten years old. The phrase ‘Planned Obsolescence’ comes to mind, as does ‘Penny Pinching’.
I was always skint until we paid off the mortgage, and every car I owned was a cheap banger needing care and attention. Economics forced me to became proficient at welding and mechanical repair, and spotting what to walk away from when buying; once two of us had the engine out of an old 9FA Mini-Cooper in less than 20 minutes, changed the shells, pistons and rings and it was back in and running again an hour later. Without exception what eventually killed all of the bangers was rust from within the box sections, sometimes in very unexpected and impossible to repair places like the A-pillars of my FE Victor.
Post-Mortgage we had two brand new cars; mine did 205,000 miles in 14 years and died rust-free because the clutch suddenly fell to pieces and there was too much damage to be economical to repair, hers did 115,000 miles in 20 years and died rust free because the cam-belt tensioner spring failed and again the collateral damage was uneconomic to repair. Both were galvanised, under-sealed and wax-injected from new. But for the surprise endings we might still be driving them now, they were good cars, much better to drive than the current equivalents from that manufacturer.
The replacement for the 20 year old was a new Mazda3. No cavity wax, minimal under-seal, and the corrosion warranty specifically excludes salt damage. Bad news: the UK is profligate with salt on the roads; kiss the corrosion warranty goodbye. But it is a brilliant car, so I paid Ultimate for full under-seal and all cavities to be waxed using Dinitrol. I hope to keep this one until we are both too old to safely hold down a driving license. This is the Daily Drive.
I walked away from almost a dozen MX5s before buying this one, all either terminally rusty underneath despite gleaming body above or with major oil-in-the-exhaust-pipe problems. I was dead lucky with the Niseko, because when I inspected the cavities I found that they had already been Waxoyled, but there were no signs of extra under-seal. I still added more Dinitrol in relevant places using squirt cans. This little beauty lives snug and dry in the warm garage, because it is the fun in the sun car, and there is no fun going out in mud and freezing slush in the damp dark.
Thank you once again for all your interesting and informative replies to my query on underbody rust protection.
Obviously rust protection has taken something of a back seat with some manufacturers, compared with what I was witness to as a mechanic decades ago.
I suppose the brand new MX-5 which my wife had as a company car from 2011 until 2015 we weren’t too worried about, because we knew we wouldn’t be keeping her (the car !) until old age, but this 2008 model we have recently purchased as a second-car, we hope is a long-term love affair, so we will certainly have to get her checked out.
Is cavity wax-oiling a better bet than just undersealing with the thick black gooey stuff? And can anyone recommend a treatment specialist around the Frome / Bristol area please?
Unfortunately, the MX-5 underbody specialist in Nelson, recommended by some members, is rather a lengthy trip from Somerset, so I don’t really think that is practical.
If anyone can recommend a similar service nearer Frome, I would be most grateful. I have found a possible one in Bristol, but so far, nobody has come forward with an actual recommendation.
I look forward to hearing from any members who might have used Ultimate Waxoil in Patchway, Bristol, or some other treatment works near to my home.
Agree that getting the cavities coated is very important but just had my 1999 Mk2 on the ramp and there are a few holes underneath where the drivers seat sits.
Just noticed a few areas of underneath stonechip coming away from the floor where the water is getting in to sit and cause problems.
Therefore, I disagree that the underneath is not important to protect where the factory stonechip has failed.
On the other hand if someone does not go to this pain in the backside job of going over the complete underneath, testing the adhesion of the factory applied stonechip around an hour and then treating these areas and other areas that have been missed or rubbed away with rust convertor, primer and topcoat which mean at least a day waiting for coats of these products to dry before applying further stonechip then just applying the goo over failing factory applied product will give nothing more than a warm feeling to the owner.
I did a 1993 ish “S” Special during the summer and it had around twenty spot areas of about 30mm x 30mm where the factory product was failing underneath and letting water sit between the stonechip and the floor of the car. We probably removed about 25% of the original underseal to be sure.
If it was my car I would have removed it all probably another day but the owner had other priorities.
Since I started this thread about rust protection for MX-5s a couple of days ago, I have now found a number of old posts on this forum from years back, dealing with this subject. Sorry if I’ve been ‘raking over old coals’ here, but I am something of a club newbee (Nov 16), and when I started it, I was surprised that Mazda didn’t underseal their cars from new, as I remember manufacturers doing when I was a motor mechanic in the 70s and 80s.
My wife and I have recently bought a 2008 Mk.3 coupe as a second car, and as we intend to keep it, it seems logical to consider the full monty (steam cleaning waxoiling the lot) after the winter. OK, so the costs seem to be around the £300.00 to £400.00 mark, which is no small outlay, but like I said, if one intends to keep a car for any length of time, especially one which has not been protected properly from the factory, it seems foolish not to.
I did find, on the internet, a chain of operators called In ‘N’ Out Centres, which advertise underbody protection fro only £35.00, and taking just 20 minutes, but I am very wary about this rapid, cut-price service - they surely cannot do a very thorough job for that amount.
Thanks once again for all info from other OC members for their help.
I would also be wary of steam cleaning before rustproofing and under sealing. Moisture in the cavities prior to spraying sealant, not a good idea I think.
Try and find an MX5 specialist with a good reputation to do the job, as they will know all the places to spray.
It should go without saying (plainly obvious), if the underseal has been damaged (loosened, scraped), it should be repaired (touching up). No statement was made about ignoring damage.
Scotland seems to be a special case when it comes to rot. Removing 25% of the underseal? Really…
Mazda does underseal cars; someone has been spreading alarmist fibs. The debate is whether Mazda should spray everything in sight on the underside or not. When you were a mechanic, manufacturers used to charge extra for undewrseal. It was called Ziebart, and wasn’t all that. Over application of underseal can lead to sink spots, and acceleration of rusting. Back then, I knew of some wierd old boy who caked his Viva in marine grease. Kept the car rust free, but it wasn’t great the look at. The rust might have been preferable.
Back in the day, 2 Mk1s, one got treated to some extra underseal, and the other did not. 20 years on, most likely both will be spending £1000 on rear arch/sill replacement. Floor repairs are relatively rare, and usually only apparentr in the most abused car (where owners have wilfully let the interior be flooded).