I'm not sure I'm picturing it correctly, but if it's very high up in a recessed entryway and weather can't get to it, is it really noticeable? Sounds like a person would have to deliberately look up there to see it. So maybe it's the just knowing it's there that is bothering you? Only other thing I can think of is, if a power washer didn't blast it out, I'm not sure what can, so maybe hang some nice decorative thing to hide it?

It's not necessary to power wash only if the surface isn't dirty. I can imagine that after 18 years, it probably is. It's just surface dirt that needs to be washed away because that may impede adhesion of the stain and you certainly don't want that. Just because Olympic stain was good 18 years ago does not really mean that it still is. I'm not saying it's not....I don't use Olympic, but painters are constantly switching brands because manufacturers are constantly reformulating and/or thinning their products to save a buck. It's almost impossible during these tough times to know which paint is good and which pant is in its sucky mode. I would only use the Jomax where there is mildew or heavy concentrations of dirt...otherwise, the power washer by itself with no cleaning solution should be enough to get the house ready for paint.

I just posted about what I used on my red cedar siding in the Deck Sealer thread. It won't leave your siding looking like it does now (it's not a clear coat), but it looks pretty good. Here is a link that might be useful: Deck Sealer Thread

I am responding to my own question. I searched and searched and found the best recipe to clean our oil base stained cedar wood exterior! The black discoloration literally "ran off" when sprayed with a simple garden sprayer and the following mixture: 1 gal water ( I used warm softened water from inside home), 4 C Clorox outdoor bleach, 1/4 C Dawn liquid dish soap. Am feeling guilty for all the times my husband scrubbed this house! After spraying with the garden sprayer, let it sit about 10 min and rinse off with hose. It looks like new siding! The company that makes our shingles also recommended something similar to clean our roof so we knew the shingles would not be "bleached".