door maintenance - what finish and how to clean

Hey all,
I've a few questions on external doors... hope someone can assist, as a search didn't provide the answers.

I have two external doors that need the (don't know the name) "piece of tread that is under the door" cleaned up and re-finished. It is dirty, but in good order and not exposed to the weather.

1. whats the name for the tread that is under the door?

2. what finish should I use? I think an oil finish or varnish was on it before, not paint.

3. the tread has no finish on it at the moment, so there is ground in dirt and no finish. Other than sanding or scraping, can I clean with "Nappy-San" like for pool/verandahs decks and then finish?

Thanks in advance,

1. Door sill
2. Most sills are merbau [red colour]
I leave mine natural ['cause that suits] & every 12 months or so [ maybe 5 years or so ] use a paint scraper to remove the grime & give it a swish of sealer oil.
A side door in a previous home was painted & was a pain to keep looking good but I suppose it depends on the overall look.
If it's merbau it doesn't take a stain really well & a painted surface doesn't seem to last with heavy traffic & is a bigger job to bring back.

Thanks.
When you say sealer oil, do you mean a Danish Oil (with a poly additive) type?

I don't know if sealer oil was the correct terminology - I use a mixture of terebin-linseed oil-kero, only because it was left over from a job in another lifetime. There may be better ready made products.
My main aim was to get away from a 'surface' coating that wears away after a period of time in high traffic areas, but there may be products on the market that others have used that stand up to the wear.

Thanks Peter, much appreciated.

I was taught that sills go under windows and thresholds under doors. ;)

Mick

I think you maybe right Mick in Qld applications.
'Sills' were adopted in Vic I think around 1937 by Grooms who didn't want to carry their wives over the 'threshold'
-" sorry dear, I can't do that we've got sills"

It's probably still tabled in the Qld parliament for discussion. ;)