I inherited some wooden patio furniture from a previous owner that looks like it's been through a lot:
I love the raw, unfinished look of this stuff, but I'd also like it to last another dozen years without being annihilated by the West Coast rain and damp. What should I do to protect this furniture that won't totally change the look?
Unfortunately there's no product that'll really do what you want here. You can certainly add protection but everything will change some aspect of the current appearance.
A good oiling (with periodic maintenance each year) will add protection, it won't stop further degradation but it will limit it. However it will also significantly alter the colouration as both boiled linseed oil and tung oil (the two main oils used for exterior applications) are some sort of amber colour and impart a noticeable yellowness once a few coats have been applied.
A good exterior varnish like spar varnish is also noticeably yellow. Also very glossy.
There are clear finishes that would provide very good weather protection, including notably epoxy finishes intended for marine applications, but they require a good film to be applied to work well and hence are also very glossy. This gloss can be reduced somewhat by rubbing down, but they'll still feel like they're coated.
Also, there's no absolute guarantee a film finish (varnish, lacquer or epoxy) will adhere properly to the wood in this condition. Standard advice for finishing is always to apply to a sound, clean surface, which these obviously don't have.
Graphus did an excellent job running down finishes and what you'll get. The one thing I would add is to keep them close to their current state and significantly reduce their decline is to keep them out of the rain. Either put them away when you don't need them (huge pain, I'd almost never bother to take them back out!) or put them under some kind of awning at or near where you want to use them. (another woodworking project!)
You could try a semi-transparent oil-based stain of the type that is frequently used for fences and decks. It is lightly pigmented and comes in a variety of colors (including gray). The stuff is easy to apply and the oil soaks into the wood with no need to worry about brush strokes, peeling or blistering. The grain of the wood still shows through and it does not have the sheen of a surface treatment.
It can be pricey, but sometimes you can get lucky with a sale.
