Teak and walnut finished in oil want two things from you: gentle cleaning and an occasional drink. Dust with a barely damp cloth, wipe dry, and skip the silicone sprays — they build a film that has to be stripped later.
Once or twice a year, when the wood starts looking thirsty, apply a thin coat of the same oil the piece wears (when in doubt, call us — we keep records of every finish that leaves the shop). Wipe on with the grain, let it sit twenty minutes, buff every trace off. That last step is the one people skip, and it is the difference between a glow and a gummy mess.
Water rings, scratches, sun fade — most of it is fixable. Bring the piece by before you sand anything.