Looking for a bit of guidance. I own a 54-plate mk2.5 in strato blue. It went in for MOT a couple of days ago and passed with flying colours. The manager (who did the MOT) called me over at the end and invited me to have a look at the under-side, whilst still on the ramp. He advised that the running rails were ‘solid as a rock’ (relief!), but there is evidence of a bit of surface rust showing. He suggested rubbing them down, using a rust protector paint and finishing with some Tetrosyl spray. He recommended this as it dries quickly and is dry to the touch (unlike a standard underseal which is waxy). I am aware there are other brands out there, e.g. Hammerite stonechip, Dinitrol etc. Does anyone have any experience using Tetrosyl? IS it any good?
Stop wasting time wondering which go is better or worse as that is all you are doing and when you decide and put it on someone else will say do not use that brand X is much better!!!.
You have rust end of story.
Rub it down and have a good look for other rust also have a look for the existing stone chip put on by Mazda that may have dried and is no longer sticking to the underside. Some cars are worse than others for this but check with a paint scrapper. Do not remove sound stonechip it will be obvious if it just rubs off that it is no longer doing it’s job.
Put on a rust convertor as per instructions again do not ask which one, just buy one and do it.
Put on some primmer and if you want a top coat that as well but I would just do the primmer.
Then get any of the various goo’s it matters not which one and put that on.
In all cases follow the instructions with each product.
Then lift the door kick plates up and spray a cavity wax into the sills with a long lance they come with Bilthamber Dynax S50 or Dinitrol Cavity Wax, not saying they are any better but it stops you asking again which one as they are both available with the long wands as others may well be. Also inside of the running rails, the goo mentioned above is used on the outside of the running rails.
Then look at this thread
http://www.mazdamenders.net/forum/viewtopic.php?f=37&t=1324
Use a small drill to get either the Dinitrol or the S50 in there.
Also and this is another weekend take the front bumper off and get some dinitrol or S50 into the front chassis rails and some goo on the outside.
You will need say 1500 ml of the cavity wax and around 500 ml or 1,000 ml of underbody goo.
Make sure the eight drain holes at the jacking points are clear with a small screwdriver and then do the cabin drains behind the seat belt towers to make sure they are clear of leaves etc.
That will sort it but remember to clean all the wheel arches and protect in there.
I use a product called aquasteel as a rust converter. www.aquasteel.co.uk Leave as it is or place a top coat
Not sure what “primmer” is. Primer? One of the purposes of a forum is to ask questions, profer an answer and discuss, not to shut down discussion at every available opportunity through a patronising attitude.
The issue with a rust converter is that it will only bond to a rusted area, and if applied too thickly are worse than worthless. Not all rust converters use the same chemistry. Tannic acid based ones contain a copolymer designed to bond with the rusted metal, with the relatively weakly acid acting as a chelating agent (Kurust etc). These are the typical ones that are blue-white in colour, and convert the surface to a black finish.
Phosphoric acid based treatments are generally green in colour, with a combination of wetting agents and dichromate. These are extremely acidic.
There are some other minor ones, such as the gallic acid based Fertan. Oxalic acid based ones, such as Rust Bust, are mildly acidic, but whereas the others contain an acid to set up the conditions for a secondary additive, oxalic acid directly reacts with the rusted surface to form a coating.
Those interested in conservation of metal artefacts found that the tannic acid based converters the most effective;
https://www.ncptt.nps.gov/wp-content/uploads/metal-paper-88.pdf
However, consider the condition of the underside. Rarely is there a pristine, grease free environment. Contaminants may reduce the efficacy of the tannic acid based treatments, the converter may fail to properly convert, and just peels off.
Jenolite comes as two products; the “rust remover”, which is sometimes also called Naval Jelly, as it was allegedly used to derust ship side rails. This is basically neat phosphoric acid. This would provide an excellent basis to prep a surface. Jenolite Converter appears to contain no acid; MSDSs list a glycol and Vinyl Acrylic Copolymer as the substantive ingredients.
By “running rails” I assume you mean the anti-drum channels that many mistakenly assume are part of the chassis. Rusting is generally from scraping over speedhumps. Mk1s aren’t galvanized, but they were zinc electroprimed, which generally does good job of limiting rusting when the painted surface is scratched. For scraped, just rub down to clean metal, and put on a non-setting underseal, that “self repairs”. On my 96, about 7 years ago, I attended to some scrapes including impact damage that caused some seams to separate. Used a drill bit wire brush, some seam sealant and underseal. Car was never garage, 7 years on, no rusting here.
My 1996 was imported in 2000, never had any additional rust proofing done, one sill needed a little patch in 2009. Never garaged, now has 270k kms. In 2017, both rear sills and arches are undergoing replacement (after 17 years UK use).
My 1993 S-Limited was imported in 2002, first UK owner spent a lot of time getting all the cavities, door casings etc coated in Dinitrol products. Car was garaged all the time, hardly driven, same service with me. Got through the MOT this year, but both wings will be replaced in the coming months due to obvious rusting (after 16 years UK use). Based on that personal experience, Dinitrol is snake oil. Others may have a different experience. One possible explanation is that over enthusiastic use of these products actually creates sink spots, and encourages pooling of water, and rusting.
Most places that offer rust protection services recommend checking & re-application of products on a fairly regular basis.
This is very funny, primmer is to primer as profer is to proffer rather like the personalities involved.
Clear and simple advice is far better than pontification in my opinion and I sincerely thank you for that Drum.
My advice for external rust - wire brush off loose rust, apply Hydrate 80 as recommended by MX5 Restorer, although any rust converter will likely do.
I don’t bother with primer although no harm in it, just paint with smoothrite and then apply Hammerite waxoil underseal(brown stuff) where appropriate.
Cavities are more complicated to access and treat but any product that gets to the right areas is better than none - dinitrol has always been recognised as a leading product in this area.
The main advice is not to delay getting the job done because you deciding between products - just get on with it.
As one or two others have remarked, your response is lengthy, rude and very patronising - no need for that attitude. Please be considerate of other people’s knowledge and experience. Yes, I will ‘just get on with it’ when time allows. Will need to buy ramps etc first.
I’d ignore him. He’s got form for being patronising and rude to other people
To the point I call it and the most helpful post i’ve read so far.
Oh dear.
I know Mr Drumtochty’s comments can come across as rather acerbic sometimes, but they all need to be taken in the spirit intended and with the info and advice that’s also provided - which from what I’ve seen is almost always very helpful.
Politeness costs nothing but does take a bit of effort.
Drumtochty posted with such urgency it was as if by taking the time to so some research the OP was destroying their car by allowing it to rust away while he/she typed!