Mazda MX-5 rust-proofing advice


Rising Star

I wondered if there are any Mazda MX-5 owners on these forums. I have just bought a 2008 Mk3 in very good condition with very little signs of rust underneath. I did see several other MX-5s before buying this one that were getting pretty bad already, even on 2007 and 2008 plates.

Rust appears to be the number one problem with the MX-5 and I wanted to do what I can to preserve mine so it remains in excellent condition underneath. Has anyone here used a rust-proofing service they would recommend or knows of a service that would do?

Thanks in advance.



Bright Spark
Hi Frank,

Rust is always a hard one with older cars, I owned a Classic Mini for a couple of years, lovingly looked after by me, belonging to a couple of mini clubs in the area.

Unfortunately there is absolutely no way to stop the problem happening eventually but you can do a few things to keep it looking tip top for the next 3-5 years at least.

1) Underseal - This is a hard one, there are plenty of makes you could actually use, none are better than others. If i'm truthful the ONLY time this option is useful is if the underside is completely dry of all moisture meaning most people would usually go through this process straight after sand blasting, primer, paint, underseal and re paint. If any serious moisture is there before undersealing it will just trap this inside making the problem worse.

2) Salt - Salted roads and winter conditions are the worst for your car, if like me you plan to use the car as a daily driver then you can't do much to stop this happening, except washing the underside of the car weekly.

3)Paint Chips - Make sure these are dealt with as soon as possible! It only takes a little chip to create a big problem, water and salt being your worst enemy, make sure you keep on top of this.

4) Wash regularly and avoid using strong products, Fairy liquid in particular is a killer. Buy a proper car shampoo, polish and wax regularly!

5)Rust bubbles... whatever you do... do not poke them, before my mini was restored I had a hole about an inch wide above my arch after poking a bubble... keep on top of these, older cars can be time consuming and pricey so just remember to enjoy what you're doing and love your car, rust is annoying and it's painful to see your bodywork deteriorate.

Like I said this will happen eventually and the only possible way to stop the spread of rust is to sand the bodywork, or if it's rotten cut it out completely, it's basically a disease and it will spread to any metal it's welded or attached too, be a bit OCD!

I will post some pictures of my mini later after work but I hope some of this helps!


Rising Star
Many thanks for your advice already.

I do have the luxury of using this as a weekend car and it will be garaged when not in use.

The bodywork is in excellent condition but then it's done less that 30,000 miles and been well looked after. It's underneath where Mazda MX-5s start to go. Even as late as the Mk3 it's still a plague.

I wondered about finding the few areas which show slight signs of rust and clean those up, rub those down and use some sort of metal paint on just those bits. My plan is to keep the car for about 4 years and sell it as a nice example still.


Bright Spark
Perfect way to go about it frank, in regards to the slight patches I would agree, treat those spots now before they spread and they become worse with more work later on, do the work now and create less later, just make sure you go through the correct processes before retreating the area and painting, as long as this is done then it should be fine for quite a long time.


Bright Spark
So, What do you think?