MX5Ireland

Just a general question - when changing the oil earlier today I looked at the general condition of the underside (as one tends to do when under a car). The floor feels solid, but there are patches of surface rust coming through (see photo below). What's the best way to treat this. I was going to give it a sand down, then lash on a dose of Waxoyl. Is there anything else you would recommend I do - or any other products you have had success with? I've read about POR15 - but is that for something more serious than what I have? Is POR 15 enough on it's own, or does it then have to be covered/sealed?

I actually called into a motor factors in Athlone looking for waxoyl but they had none, and the guy insisted that I take some brush on Tetrosyl Seam Sealer - saying it would do the same thing. I asked if it was not meant to do just what it said on the tin.... seal seams, but he said it could be used to cover the whole underside of the car. Despite my doubts, I bought a tin, but when I got back home I googled and it seems (no pun intended!) thats this is not the case. From a few forums I looked through it appears that this stuff is put on over seams (or in some cases over the whole underside) THEN covered in stone chip. I was hoping to get away with just the stonechip/waxoyl layer. I intend returning the seam sealer - unless convinced otherwise!


Thanks.

As you stated, seam sealer is really for sealing the seams. If you spread it out enough to cover what you need it will peel off in no time. I’m sorry myself that I hadn’t used the por15 when I did my car, from this link it looks to be about the best stuff
http://polishnparts.ie/por15-black-rust ... -us-quart/

Thanks for the link - and the write up makes it a very tempting proposition. Having read it, however, I think it would require me removing the underseal already on the car as it goes directly onto bare metal (?) - that's a much bigger job than I'm prepared for at the moment. I have a feeling I'll end up just sanding and touching up with stone chip. I'm looking for something that lasts well - and maybe a layer ot two from a can of spray on stone chip will do afterall.

Graham, it just goes to show that some folks working in the trade don't really know what they are selling to customers. What about the black body shultz that repairs shops use ?

True. The first guy I was dealing with thought it should be OK, but called out the manager - who was in no doubt it would be fine to use as a sealant for the underside of the floor. I'm going back tomorrow to see what else is available - or get a refund and look elsewhere.

Not that I'm an expert but the guy who fixed the rust problem on my car mentioned he used black Shultz to stop the rust coming back (after scraping off the rust first).

Schultz is only bitumen based paint. All rust needs to be treated/repaired first otherwise its only cover up job. There are some fantastic 2/3 pack under floor coatings, after rust treatment of course. I used Cobra Truck bed liner on last few cars and it can be tinted to colour but floor must be absolutely clean and rust free. The Cabra is excellent product and " real" protection, hard shell , but slightly flexy underneath . Great stuff !!

Then we supplied /fitted they newly powder coated suspension, subframes etc. Looks better then new