You can use a gel dye to restore color. Gel dyes are ideal for the restoration of old furniture. The best part is that you don't need to remove the original old color from your furniture. Gel dyes can easily restore the faded and worn color of wooden furniture.
While you can apply a new coat of oil (such as olive, tung, or linseed oil) from time to time to furniture that originally had an oil finish, it's not a good idea to apply oil to wood that has been finished with a built-up finish, such as paint, shellac, lacquer, or varnish. Wood will naturally acclimate over time to the relative humidity of its environment, regardless of whether it is finished or not, although finished wood will take a little longer to adapt.