In message , "Dave Plowman (News)"
writes
In article ,
Theo Markettos wrote:
Thanks, that's really useful. So you'd suggest separate coats of
penetrating light WD40 or Waxoyl, and then mixed Waxoyl+underseal? I
have areas of failing underseal (coming off in lumps) - is it worth
pulling this off (might be a bit like peeling an orange - get more than
you bargained for) or slapping penetrating stuff on it and then
underseal mix on top?

If underseal is peeling off, the rust will have got some way past the
edges of the loose bits. I remove the loose bits then some way round the
edges with a hot air gun. Then sand down to bright steel, apply a zinc
rich primer, then underseal.

That's fine if there are only a few, isolated areas of rust. When
there's a lot of it, it's usually less soul-destroying to abandon
attempts to do a 'restoration' job, and concentrate more on damage
limitation, as I have described. If the rust hasn't really got a hold,
it's often better to leave it in place. The WD40, Waxoyl and Dinitrol
(which I haven't used myself) will soak into it and slow its progress -
especially if you can break its surface first (by scraping or using a
wire brush).

Waxoyl is far from the best of those sort of things. Have a look at the
Dinitrol range.

As I've said, I've never tried Dinitrol. I always wondered what it was
like. At my time of life, I no longer drive the rust-buckets we used to
have to make do with in the past. Hopefully, those 'happy hours' of
hacking at the underside of cars are over!
--
Ian