I’m often asked how frequently a watch should be serviced. This kind of depends upon the watch. In the early 1900’s, watches were lubricated with natural oils, often refined whale oil or porpoise jaw oil. Due to their organic nature, they would break down a lot quicker than modern oils that are synthetic. Consequently, watches had to be serviced on a much more regular basis….every year was not uncommon. Additionally, many watch cases were not nearly as dust resistant as they are today. So between dust and lint particles getting into a watch mechanism as well as natural oils breaking down, the watchmaker was kept pretty busy with a regular flow of watches.
Knowing that many of my customers don’t have a watchmaking background, I often opt to the analogy of the car. Most manufacturers recommend changing the oil and filter every 3000-5000 miles. This is because the viscosity of the oil starts to break down and the oil also begins to take on engine particulate. A car will not run as efficiently or maintain a long healthy life if the oil is not changed on a regular basis. The same holds true for a watch.
Below is the center wheel from an American pocket watch, ca. 1900. The pivot (bearing surface) in the image on the left is what happens when the watch has not been cleaned regularly. This pivot was running in a brass bushing (much softer than the hardened steel pivot) for so long with inadequate lubrication, that the steel pivot was worn down significantly enough to almost render the watch unusable without repair or replacement parts. The image on the right shows the same pivot after it has been burnished down in a lathe to attain proper shape. Consequently, the bushing for that pivot also had to be closed to accept the now smaller pivot.
The tick of a mechanical watch is a jewel hitting the escape wheel. In many watches, that happens more than 80,000,000 times a year. If not properly lubricated, there will be wear and tear and the cost of servicing the watch will begin to rise.
As a general rule of thumb, I recommend that a watch be serviced every 5-7 years. More regular maintenance would be assure a longer life to the watch but is not absolutely necessary. And some manufactures suggest this. And certainly, if your watch starts to exhibit erratic timekeeping, it's a good idea to have it looked at and possibly serviced.