The pure oils are expensive, more rare and take more time to cure but have been said to produce the best finish.
Unfortunately they're most usually found mixed with other things but do contain a percentage of the oil. Just not pure. They can be purchased at your local hardware store.
Teak oil is a bit darker but tung oil tends to bring out the shine in the grain. You put it on a rag, wipe down the stock, wait a couple of minute and wipe off the excess.
It cures in 24 hours and you repeat the next day. The more coats you build up the more prosperous shine that will come.
(teak oil)
The first and second stock were finished in tung oil. The first had around 15 coats.