Don’t be fooled into thinking that you should use a product labeled “Teak Oil” on teak wood, either exterior or interior. Teak Oil is a marketing term. It has nothing to do with teak. Teak trees aren’t squeezed to retrieve the oil.
Brands of teak oil can be anything from simple mineral oil to thinned varnish to blends of linseed oil and varnish. Most are blends of linseed oil and varnish.
Mineral oil never dries. Thinned varnish dries to a hard film. Blends of oil and varnish dry to a soft, sticky film if all the excess isn’t wiped off.
The natural oil in teak is not something that needs to be replaced, anyway. In fact, this oil is often a problem for finishing because it prevents finishes from drying and bonding well.
If the teak you are concerned with lives outside, I suggest you simply leave it entirely unfinished. It will gray with exposure to sunlight and rain, but it will resist splitting and it won’t rot. It will last a very long time.
No finish, including “teak oil,” will prevent the graying, and hard-curing film-building finishes will peel and become a mess after a few years.
If the teak you are concerned with is inside, I suggest you apply a film-building finish, such as varnish, lacquer or water-based finish. A film finish will provide the best protection against liquid penetration. (Keep in mind that Danish teak furniture is finished with a thin coat of very durable conversion varnish, not oil as is sometimes claimed).
Especially if you’re using varnish, but also with other finishes, you should wipe the wood with a quick drying solvent such as naphtha, lacquer thinner or acetone just before applying the first coat of finish to remove the natural oil from the surface. Then apply the finish quickly after the solvent flashes off (dries)—before the interior oil has time to work its way to the surface.
You don’t have to do this with additional coats because the first coat seals the natural oil in the wood.