Since the neck is finished only with gunstock oil and wax blend, it is more susceptible to humidity changes. An occasional truss rod adjustment will halp keep your bass playing factory-new. If you are getting fret buzz (plugged in only, of course) raise the action by turning the trussrod wheel counter-clockwise, to lower the action turn it clockwise.
An infrequent dose of gunstock oil will help to keep the neck maintained; we recommend and use Birchwood-Casey Tru-Oil, but any good quality gunstock oil will work. Clean neck first. Use a small amount of Tru-oil, leave it on for 5 minutes, then wipe it off with a paper towel. Then apply Birchwood-Casey Gunstock Wax. Be sure to douse the paper towel with water before disposing of it! Read the wax and oil manufacturer's instructions regarding disposal of these used paper towels.
Birchwood-Casey products are available at most sporting goods or gun stores, or direct. Their web address is http://www.birchwoodcasey.com.
Rosewood fingerboards should not be treated with gunstock oil; instead they should be treated with a high grade of lemon oil.
For cleaning, try using the same high grade of lemon oil to clean the entire neck, both maple and rosewood fretboards. Keep in mind that if the dirt or grease has been worked into the wood, it cannot be removed except by sanding it down, which we do not recommend unless exercised with extremely fine sandpaper (1200-1600 grit), and even then very sparingly. It is better to keep it clean in the first place. Washing your hands first helps!
Some discoloration after many hours of playing is normal on unfinished necks.
Be sure to follow all of the manufacturers recommended safety precautions when using any of these oils or waxes.