The mainspring is the heart of the timekeeping of any spring drive clock. If the mainspring is not oiled properly the clock will not work. The oil that is used is absolutely critical ; it must be able to work in a slow moving environment and it must be able to resist evaporation for many years. It is also very important that the oil be absolutely non corrosive. In my opinion the mainspring grease that is available through the various suppliers is probably the best to use Listen to the mainspring unwinding as the strike runs if you hear the mainspring clunking or making a snapping noise : then the lubricant probably isn't working. If this situation exists in the time mainspring then the clock will not keep time and may not even run at all. Mainsprings in the older clocks that have been around for many years have a buildup of hardened oil that is not removed by the ultrasonic process. This must be removed, or the clock will not work.The mainspring will stick erratically and cause timekeeping problems, and may actually bind up and release suddenly and cause a tooth on the spring barrel to be bent or even bend a tooth on the second wheel. If this happens when no one is there to hear the spring snap, then you will be befuddled when the thing just stops working after a careful overhaul.I have used 0000 steel wool on mainsprings; have also tried very fine emery paper #1000 or crocus cloth. The problem with using emery paper is that extreme care must be taken to remove all of the residue from the cleaning with the emery paper or the mainspring will be worse that it was before it was cleaned.After the mainspring has been cleaned and polished, a clean soft light colored cloth can be used to remove the residue ; then run the spring through the ultrasonic cleaner.
To oil the rest of the clock use clock oil. Do not use anything else. You can buy clock oil from parts suppliers. Do not get any oil on any of the gear teeth. If you do, the clock mechanism will be destroyed quite soon. Clock gears are brass. Clock gear pinions are usually steel. Steel is harder than brass, usually. The oil on the brass gears attracts dust. Very soon there is a grinding compound on the gear teeth from this mixture and the teeth of the brass gears wear away rapidly. Oil the pivots, pallet working surfaces, and impulse arm. Do not slop oil on the ratchet dogs. The oil will thicken up and make the ratchet bind, usually destroying the ratchet, key, ratchet dog, mainspring, second wheel, the users fingers and fingernails, and possibly the dial face.