Oiling is one of the oldest treatments for preserving and finishing wood. Originally, linseed oil was used, which is derived from flax and dries by oxidation. Today, oil finishes are very popular, as they can be restored and maintained very easily. Unlike some varnishes and sprayed finishes, they do not conceal the wood's grain, but enhance it. However, oils do not have resistance or protective qualities of more modern finishes and oiled surfaces are likely to become marked by wear and usage.

Teak & Danish oils dry faster than Linseed oil, and they are the easiest to work with. Waterlox is a great product if you are considering using tung oil.

Tung Oil: 

Tung oil or China wood oil is a drying oil.  As a drying oil, tung oil hardens (dries) upon exposure to air. The resulting coating is transparent and plastic-like. When applied in many fine coats over wood, tung oil slowly cures to a satin sheen with slight golden tint. It resists liquid water better than any other pure oil finish, though it still provides little protection against water or scratches. Tung oil does not darken noticeably with age and is claimed to be less susceptible to mold than linseed oil.

Tung oil has become popular as an environmentally friendly wood finish, but it should be noted that many products labelled as "tung oil finishes" are actually polymerized oils, wiping varnishes, and oil/varnish blends.

Linseed Oil:

Linseed Oil is a drying oil. A linseed oil finish is a simple to produce, but extreme care must be taken with the oil soaked rags. The rags will heat up as the oil dries resulting in combustion and a fire!  This is no joke, as I have experienced it first hand. Dispose of used rags by dousing them in a bucket of water.

The downside of  linseed oil is it drys slow and new wood will require a number of coats. Boiled linseed oil dries much faster than raw linseed does, and it's the better choice for most applications for this reason.

Teak & Danish oil:

Teak & danish oils dry faster than pure oils, and provide better protection to the wood. Some are actually blends of oil & varnish. Some of these oils are tinted with color. They all include dries and some include tung oil to enhance the protective nature. Danish oil is a lower luster, while teak oil give a little higher sheen. You can also buy pure tung oil. It's used in a similar fashion as danish and teak oils.

Oil Varnish:

An even stronger oil finish can be achieved by mixing linseed oil and varnish. Oil varnish can be bought ready mixed, or you can make your own using 2 parts mineral spirits (or turpentine) and oil to one part varnish.

How to Apply:

Oil finishes can be used on most woods to bring out the natural qualities of the grain. Apply the oil with a soft cloth. Load the cloth with enough oil to apply a wet even coat to the entire surface.

Next, rub the oil evenly into the whole surface. It is important to check that the grain is completely wet, otherwise the finish will turn out patchy. Use circular motions first, then straighten up and follow the grain.

Leave the oil dry overnight. Some deep grained woods will have soaked up most of the oil, leaving little on the surface. Lightly sand with 320 sandpaper. Apply further coats until the desired look is achieved, leaving each coat to dry overnight. Three to four coats is usually enough.

Drying time varies between hours and days depending on the type of oil used. When dry, take 0000 steel wool and rub the surface down to give it a final sheen. Rub in the direction of the grain, keeping an even pressure over the whole piece.

Finish by burnishing the surface with a clean soft cloth to remove the dust from the steel wool.

IMPORTANT NOTE :

To prevent fire or hazards...discard rags by soaking them in a bucket of water. Oils heat up upon drying and can ignite and burst into flames causing a fire. Once soaked in water overnight, the rag is safe to throw away.