*** To service or not?
Why does a mechanical watch need servicing? How often should a watch mechanism be overhauled? What exactly needs to be performed? How long does it takes and what is the service cost?
Glad you've asked!
A 'proper' understanding of watch servicing should be of great importance to any watch owner, let alone to a keen watch collector. Let's start form the very beginning.
On a cold day when you rub your hands, you do so to warm them up. Rubbing creates friction, and the product of friction is heat.
The key word here is FRICTION.
In real life friction could be both desirable and not-so-desirable. For example, the top side of surfboard is coarse so you can have a good grip (more friction = better grip). The bottom is polished and as smooth as possible (less friction between board and water = better surfing).
When it comes to mechanical watches, friction is the evil of all motion. Friction reduces the driving force, increases wear and tear and, has a very negative effect on time keeping and accuracy.
Friction is bad. And this is the first thing to remember.
Now here is the good news: over the centuries, watchmakers have worked hard to get rid of friction, or at least to minimize its negative effect on watch performance. Friction between two surfaces (for example a watch pivot and bearing) can be reduced if both surfaces are highly polished. Reducing the size of contact area also helps. But what helps most is lubrication: when a small quantify of oil or lubricant is applied between solid surfaces, the friction is greatly reduced.
So second thing to remember: OIL is a good thing!
There is however one small problem: over time, this ‘good’ oil turns into ‘bad’ oil. After 5-6 years of constant ticking, a watch which has kept correct time no longer does so because the good, fresh oil has deteriorated to the point where it no longer act as a lubricant.
So here we arrived to the third point: oils and lubricants AGE with time.
In fact, not only do oils get worse to the point where they serve no purpose, if the watch is forced to run beyond that point things get really bad. After 7-8 years, the watch mechanism is seriously contaminated with dirt, dust and metal particles which are now embedded in the old lubricant. The mixture acts as a grinding paste – completely opposite form the very reason we lubricated the watch in the first place! After 12-15 years those fine, hard and polished pivots and jewels are now badly worn.
To answer your first question: a watch mechanism needs servicing because old oil needs to be replaced with new, fresh oil which will restore watch performance. As you guessed, this should be done each and every 5 years.
When you think of it, this is no different to grease and oil replacement in your car - except in one significant detail: the amount of lubrication in watch is minuscule. You cannot simply drain the old oil, replace the filter and voila- off you go!
In order to apply fresh oil, the watch mechanism needs to be dismantled completely. Worn out parts are replaced and all components are thoroughly cleaned, de-greased, dried, then re-assembled, lubricated and finally adjusted for good timekeeping. The watch is left to run for a few days and if needed, re-adjusted again.
[Gents and ladys Rolex Dateust dismantled, ready for cleaning]
This is what watchmakers call a complete overhaul.
The process is tedious and time consuming. A complex watch mechanism like an automatic chronograph (stop watch) may contain over 200 components. In addition, the watch case itself may need polishing and in case of water resistant watches, replacement of rubber seals and in some cases replacement of the crystal, pushers and winding crown. Finally, the watch bracelet is cleaned and polished to give the watch a desirable "as new" look.
There is no fixed charge for a complete overhaul - the more complex the watch, more time it requires to service. In addition, watchmakers often estimate the repair cost based on overall condition of the watch. A well 'looked after' watch would need less work than a watch worn daily for 20 years. With some exception, vintage watches (40+ years old) are rarely serviced by the manufacturer. In their view such watches are simply too old and spare parts are hard to obtain. Those watches may require special attention and the repair costs are usually higher. Finally, well known 'brand name' watches and those made of precious metals and studded with diamonds cost more to service due to higher insurance costs / risk, undertaken by watchmaker.
A turnaround service time of 4 weeks is industry standard, except for vintage watches or watches which need more serious repair (broken parts, water damage, shock-related issues etc).
To conclude: if you would like to extend the life expectancy of your timepiece, follow the manufacturer's advice and service it when it's due. Wearing the watch for extensive periods of time without an overhaul will cause irreversible damage which will have undesirable consequences to time keeping - even after such watch is overhauled at some later point in time.
Mechanical watches - like any other precision instruments - are not built to last forever, and especially not if abused and forced to run to point of self-destruction.
Contrary to popular web myths, placing the watch on a watch winder "to keep the oil fresh" will not extend the ‘between service time’.
If you have a number of watches in your watch collection and only wear them once per month or less, you may get away with an additional year or two between two services. But beyond that, such watch should not be worn again unless overhauled - it should be only good as 'display' model and as such left to rest, unwound and not worn, until you decide to service it and wear it again.