Courtesy of Fred Cicetti:

"Check the KLARINET archives on this one. Lots of stuff.

In short, use an organic oil such as almond or olive. You can get almond in a drug store. Many experts say it's the best for grenadilla.

Unless you're in a very dry climate, once a year is enough. Apply oil very lightly with an old swab. Let the horn sit overnight. Don't get it on the pads. You can put pieces of paper or cellophane under the pads to make sure no oil gets on them. Wipe out the excess next day."

Buffet does not recommend oiling new clarinets. Francois Kloc, Manager for Buffet Instruments N.A., has mentioned in Klarinet (check the Archives) that he oils the older clarinets when they look dry and start having light checking.