Wood flooring and exterior doors require a tough finish to protect them. The choice is usually between varnish and oil.
Oil finishes such as linseed oil and Chinese tung oil work by natural oxidation and self-polymerisation of the organic molecules to form a hard skin. Traditionally the finish would take several days to dry and was reapplied once a week, then once a month, and then once a year. This gives a rich colour and a fairly durable finish. Clean and recoat every year to maintain the finish. It is easy to cover worn patches.
Modern oil finishes have solvents, such as white spirit, and a dryer, usually terbene. Some also have a plasticiser. These ingredients make them very similar to modern varnishes.
For a traditional option, make an oil finish called a 'long' varnish by adding 30% boiled linseed oil and some turps to an ordinary varnish.