Most often associated with gunstock oil, this is an excellent choice for a guitar finish, especially on necks. Birchwood Casey Tru-Oil is a blend of boiled linseed oil and other natural oils that can really make the grain of a guitar stand out.
Tru-Oil on a guitar neck gives a sliky feel that makes the guitar seem extremely fast. One negative to tru-oil is that it does not provide as much protection as a lacquer finish. Many people like to utilize lacquer for the guitar body and tru-oil for the neck. This gives the body more protection from dings and still allows the neck to play at its best.