As a watchmaker I am am often asked what is the correct interval for service, and my response it always the same - it depends.
I have answered this question before in several threads here, but I thought starting a new one might help keep this information where it can be seen, and not buried in another thread. It’s also an opportunity for me to consolidate some points that I have posted in various places.
Just a disclaimer to start with - for those who are convinced that there is no need for regular service, please note that I am not trying to change your mind, and I’m just giving my perspective here. I know someone out there will either think or write “Yes but as a watchmaker, you have an interest in getting more business!” If you saw my backlog of repairs, you would realize how ridiculous that idea is. If you are a good watchmaker, getting business is not ever a problem – having far more than you can handle is.
In my opinion, there are many things that can come into play regarding how often one should service a watch. Is the watch modern, or vintage, and how available are parts? Do you take it to a service center, or use an independent? My answer for a specific watch can be different depending on those factors listed. Also, it's a personal decision, and some people will be confortable leaving the watch until it stops, and some won’t.
So let’s look at a few common things that are regularly talked about, and some factors that I think are important, in detail:
1 – “Because I only wear my watch 50% of the time, I should be able to double the time between service.” If the watches are actually stopped for X% of the time, then yes the service interval can be extended. However it's not a completely linear relationship, because eventually oils will break down (yes even modern synthetic oils) regardless if the watch is running or not. So if the normal service interval is 5 years, and you wear the watch 33% of the time, the service interval does not now become 15 years. The oils will dry out long before that. In fact most brands require that the oils I use at my bench are no more than 2 years old – yes they will check this during shop inspections. Now this does not mean oils are only good for 2 years, but that 2 years, added to the recommended service interval, is all that they feel comfortable with in terms of the age of the oils.
2 – “As long as my watch keeps good time, there no need for service.” Timekeeping is not a reliable indicator that a watch is in need of service. I see watches often that keep great time, but are a mess inside as there are many components inside a watch that are not directly related to the timekeeping function. Certainly if your watch suddenly begins to lose or gain time, this can be a sign it needs service, but the absence of a change, which is what some use as an indicator of "everything's fine inside" is certainly not true.
So what do I mean when I say the watch is a mess inside? Here are some examples:
Rolex Cal. 3000 that came into my shop “running well and keeping great time”
Balance jewel is completely dry:
Oils dried and crystalized:
Here is another dry pivot – you can see products of wear in the jewel:
Panerai 005 with excessive wear on the main plate and barrel bridge from the winding pinion:
Debris through the movement:
Wear on the barrel bridge of an ETA 2824-2 – I see this wear often on this movement:
The main plate was also worn, requiring the whole plate to be replaced – not an insignificant expense:
Wear in a Rolex Cal. 1575 barrel – deep groove worn on the inside wall of the barrel - worn barrel on the right, new barrel on the left:
Worn bushing (hole was oval shaped) for the chronograph runner in a Tag chronograph (ETA 7750):
I replaced it with a jewel:
I could go on, but you get the picture I hope.
If the oils are dry, then the rate of wear is accelerated. If that wear is significant enough to require replacement of parts is something that has to be judged at the time of service. Certainly in some of the cases above, parts had to be replaced, but even parts that are not worn completely will potentially affect the performance of the movement over time.
So the watch may run and run okay, but over time the performance will degrade, and the parts will eventually need replacing. In some cases excessive wear that will happen when the lubrication dries out will not result in a huge additional expense at service. In other cases, it may more than double the cost of the service. If the wear is on a spot where the part is small and is easily replaced, then the cost is likely to be low. If the wear is on a larger piece like the main plate, then those are never inexpensive. For example a jeweled main plate for a Cal. 1128 is a $250 item – far different than replacing a wheel that is only $15 or $20.
3 – Modern or vintage? If you have a modern watch, it’s not something really rare, and parts are readily available and not expensive, then wearing the watch until a problem appears is not necessarily a bad idea. It really depends on what the movement is, and where the weak spots are. For vintage watches, my advice is quite different. Now to use a vintage Omega example, if you have a Cal. 321 Speedmaster, then you probably know that most of the parts inside this movement are discontinued (no longer sold by Omega), and some are very difficult to find. If you do find them, the people selling know they are rare, and these parts are very expensive. In a case like this, the priority should be on regular service in order to preserve the parts inside the watch as much as possible. So if someone asks me how often to service their Speedmaster, my answer will be different if it’s a Cal. 1861 watch, compared to a Cal. 321.
4 – Service center, or independent? -One of the issues with using a manufacturer for service is their "take it or leave it" attitude with what they feel has to be done. They in effect hold you hostage, and if you don’t agree with all that they recommend, they will refuse to do the service. There are reports of things like a watch that needed a new crown getting a complete service that would seem to be completely unnecessary. Be aware that built into the cost of every factory service are the exchange of parts that are replaced whether they need it or not. This is one reason why factory service can be much more expensive than using an independent who replaces only what needs to be replaced. So if you plan on using the factory, you are already paying a premium for parts replacement that is built into the service cost, so if some parts are worn, they won’t charge you any extra. However you are already paying much more to start with.
5 – Is water resistance a factor? – One thing to keep in mind is that there is more to maintaining a watch than it’s movement. For a watch that has water resistance built into it, seals will degrade over time even if the watch sits in a drawer or safe. Part of servicing a watch is the checking and replacing of seals, and pressure testing the watch to check it for water resistance. I always recommend that anyone who gets their watches wet regularly, also has pressure testing performed on them regularly, even if you don’t get a full service done. If the watch fails the testing, at the very least get the seals changed.
So what to conclude from all of this? One is that you need to be comfortable with whatever approach you choose. Some people view this from a purely economic standpoint, and don’t really mind the idea of parts inside their watch wearing away. If you want to let the watch run until it stops, that is your choice and I personally have zero problems with that. Just don’t be under the illusion that because a watch performs well, it does not need service or that parts are not wearing inside.
Others don’t like the idea that the watch is wearing itself out, so they prefer to service more regularly, and that’s perfectly valid too.
My key point here is that applying a single set of rules for all circumstances is not necessarily the best approach.
I hope this helps.