You need to treat the wood according to the finish. If it's been varnished or laquered use wax. If the wood has been oiled for a finish, then you need to use the same type of oil used in finishing the stock. In oils, there are "raw" oils and modified oils like "boiled" linseed oil which may be heated as part of the modification or only had one or more driers added. Same with tung oil it may be raw or treated. You may also want to wax an oiled finish to protect it from water.
The difference is that raw oils will never dry, are always wet, and the oil finish stays soft. A "boiled" oil is one that has had a modifier added to it so the oil molecules will link together or "polymerize" and dry. As part of the drying process, the oil will heat up which is why you should not put oily rags in the trash - they can catch on fire. Oil rags are usually kept in a jar or closed container so they cannot combust. If you want to throw them away, wash them in detergent and water first to reduce the amount of oil in the rag.
In use, polymerized oils penetrate to a certain depth and then harden. As additional coats are added, the oil will build up in layers on the top of the first hardened oil layer so that, in the end, you end up with an oil varnish finish on the surface.
With an oil finish, if you wet sand the coats (with oil) it forms a slurry that acts as a grain filler and helps smooth out the finish. This is how "Danish oil" finishes are done. The nice thing about an oil finish is that if it is scratched, you can wet sand the finish using fine sandpaper (320 - 400 grit), smooth out the scratch and with a couple of applications of oil - the stock will be as good as the day it was first finished.
Pledge is one of the worst things you can use on furniture or wood. It contains silicone which is what gives it "shine." Plain wax is far better protectant than Pledge.
One of the best wood cleaners / polishes is
Craftsman Furniture Polish as it is compatible with oil, shellac, varnish, and lacquer finishes.
For any type of finish, a plain paste wax (including a good automobile wax like Zymol or Pete's 53) is the best protection you can have. On oil finishes the wax is easily removed to apply another coat of oil by wiping the surface with mineral spirits or turpentine, and then oiling the stock again.
Most paste waxes (with the exception of Zymol and Pete's 53) use a petroleum distallate to liquify the carnuba wax. Directions for application usually include waiting for the wax to "dry" before buffing. What you're really doing is waiting for the petroleum distallate in the wax to evaporate.
In both Zymol and Pete's 53 the carnuba is liquified using banana oil and almond oil. With those type of waxes you wipe the wax on in a thin layer, and then buff it off immediately as the oils become part of the wax finish.