I want to stain the door mainly for UV protection.

Stain will not provide UV protection. What you need is UV-resistant topcoat.,

Can you link to the manufacturerâÂÂs web page for that product? Is that the door manufacturerâÂÂs requirements?

Oh, I thought, just like with deck stain, that color itself acts as a layer of UV protection. I don't want the fir to turn a silver grey color. I do understand, as you say, that there are topcoats that provide UV protection.

Here is a link that might be useful: Simpson Doors

Interesting! I don't know what the heck a stain with sealer in it is. It's true that deck stains have UV protection, but these are not meant to be topcoated. I have always just used a stain (standard interior wood stain) and then applied multiple coats of some exterior varnish. For something like this, you should look into the Sikkens Cetol Door and Window finish. It comes in 4 colors plus clear and is pretty much my go-to product for varnishing exterior doors.

Here is a link that might be useful: Sikkens Cetol

Lots of work, but I stain and apply 4 coats of marine spare varnish

Here is a link that might be useful: varnish

paintguy, I hear what you are saying about, "what the heck is a stain with sealer." I'm thinking it may be an error in the literature?

christophern, I think I may follow your advice on finishing the door. I saw a lengthy video last night that explained the steps involved with finishing an exterior door with spar varnish. I've provided a link below.

I still have two questions:

1. Can I forgo using any stain at all, leaving it natural, and just finish the door with Spar varnish. Will I risk the door turning grey?

2. Can I use Spar varnish on the interior side of the door too?

Here is a link that might be useful: Finishing an exterior door

Another thing.

Would it make sense for me to do a spar finish on the outside and sides and a tung oil finish on the inside?

Actually, I suspect the literature that comes with doors these days is written in a way that makes it hard to comply with the instructions so that when you have a complaint, they can say hey it's your fault you didn't use a SealerStain!

You do not need a stain. You can just apply the varnish directly to the wood, but be aware that the oil varnishes have come amber color so the color of the door will change so test it at the bottom first to make sure you will like it. You can use the exterior varnish inside but this is not really necessary as the interior varnish will be durable enough. The main problem with using the exterior varnish is the smell and it also takes many hours to dry.

I believe the manufacturer is calling for a product like Minwax Polyshades.