Sill rust query

davey_g10 · 2025-11-10T19:08:25+0000

Hey all,

I'm currently looking for a new replacement used car after having mine sent to car heaven by a lovely young chap who hit the side of it.

I've found one that otherwise ticks all the boxes but noticed some rusting on/around the sills. I spoke to the garage about it and they seem to think it's just surface and there are no advisories on the current MOT, and have never been advisories on any MOT regarding it.

In the opinions of those here, is this a concern? Reason to walk away? Acceptable if treated?
My car structural knowledge is limited so really appreciated thoughts on this.

Further details if it helps: 66 plate (early 2017), Kia Rio, spent a lot of it's like around Edinburgh (probably why there's some rusting)

SonicSW20 · 2025-11-10T19:18:25+0000

Its under the protective coating, it will continue to get worse and become a problem if its not dealt with.

davey_g10 · 2025-11-10T20:29:37+0000

What kind of fix would I be looking at for that?

sigma · 2025-11-10T20:34:58+0000

davey_g10 said:
What kind of fix would I be looking at for that?

The proper way is to grind/blast it all back to clean metal and recoat it.

The bodge/simpler path people go down is to apply rust converter and then coat over that.

bainbridge · 2025-11-10T20:39:52+0000

It does look like surface rust, rather than rusting from the inside out.

Not bad for an 8 year old car that's spent time on the Scottish coast.

You could wire brush away the loose rust, then treat with rust convertor and spray on some waxoyl. That'll cost about £30 if you did it yourself.

Or, you you could do the same prep and use a more expensive sealer, like zinc primer or mastic epoxy.

Tbh I'd just do the above with waxoyl. You'll never stop rust, only slow it.

davey_g10 · 2025-11-10T20:46:06+0000

Thanks very much for that! So you wouldn't necessarily write off this particular car for that type of rusting? Typically, if treated, would that prolong the life of the car for quite a number of years?

radderfire · 2025-11-10T20:51:45+0000

davey_g10 said:
In the opinions of those here, is this a concern? Reason to walk away? Acceptable if treated?
My car structural knowledge is limited so really appreciated thoughts on this.

Yes it's a concern.

Yes, walk away, find a car without rust, it should be possible.

The car won't fail an MOT until the rust is weakening the car structurally. The rust is an indication that at some point in the future this will happen, and when it does, it will be a £500+ bill. So, I would walk away.

There are so many second hand cars out there, you should be able to find one in better condition. It should be possible to find one at this age with no rust, but it will take some looking.

radderfire · 2025-11-10T20:56:16+0000

davey_g10 said:
Thanks very much for that! So you wouldn't necessarily write off this particular car for that type of rusting? Typically, if treated, would that prolong the life of the car for quite a number of years?

I would. Be fussy, look around, wait until you find a perfect or near perfect car, they are out there.

I would say maybe two years on this car before the rust starts getting really bad. Avoid.