Well, since we've tiptoed around the issue, here is an explanation purportedly from Breitling posted on the old forum before the crash. Of course the material he is speaking of is Nivarox. I would imagine Omega is very similar. Like John, all Omegas I purchased new ran to COSC out of the box, but who knows how long they were in the box. Undoubtedly the watch in the original post in this thread is indeed in need of service. This is just some food for thought, guys. Cheers, Bob
Breitling COSC and Hairspring
OK, I decided to go ahead and post the full details now, since I am satisfied as to the veracity of the material I am about to reveal.
After re-checking the accuracy of my Chrono SA which I purchased new 3 months ago, I am pleased to report that the daily rate error has indeed improved sufficiently to meet the limits imposed by COSC certification. The initial error was approximately +8 to 9 sec/day and is now running at +5 sec/day, and is expected to improve even further, although this is expected to be a relatively small further improvement. At least it is now within official COSC requirements which allow for a range of -4 to +6 sec/day. And now I'm a happy camper!
The reason for the improvement in accuracy has very little to do with the lubricants, but rather has to do with the hairspring. For those who don't know what this is, it is the tiny spring attached to the balance wheel which supplies the regulating influence on the balance wheel. Allow me to explain:
About 3 years ago, when Breitling decided to convert to 100% COSC movements, they needed to change the hairspring to a temperature-compensated type in order to maintain accuracy over the temperature range imposed by COSC. But they also decided at the same time to improve the mechanical shock resistance of the hairspring, i.e., to make it more rugged. So they adopted a special alloy to accomplish this goal. The only real drawback is that this alloy does not reach its ultimate long-term temper until it has been exercised over a period of about 3 months. This is not a flaw in the alloy, it is simply a property of the alloy that must be accomodated.
This new hairspring is initially stiffer than a normal hairspring, but it will gradually soften a bit during the first few months of wear. This causes the natural resonant frequency (the oscillation rate at which the balance wheel/hairspring assembly "wants" to run at) to run a bit faster at first, but which will gradually slow down to the final rate which then causes the watch to be in compliance with COSC accuracy requirements. Since it is more desireable to have a watch that doesn't lose time, it is necessary to set the regulation a bit fast initially. In other words, if the watch were regulated to run initially at +2 sec/day (which is well within COSC) after the first few months, it would settle down to a rate which is in the negative portion of the COSC range. As this would be unacceptable to many Breitling owners, they decided to set it faster than watches with ordinary hairsprings. This way, after the break-in period the watch will slow a bit, but will remain on the positive side of the COSC range. Makes perfect sense when you think about it.
So if you've just bought a new Breitling be sure to give it a few months of daily wear before checking the accuracy. Never thought I'd believe or accept this, but now that I know the real reason for my watch initially running too fast, I am no longer unhappy about my experience with the Chrono SA. In fact, I am delighted that Breitling has addressed some very subtle issues with the hairspring.
This information came directly from Breitling SA and I trust you will all find it enlightening. And what really surprised me is that some people at Breitling regularly view comments on this forum about their watches, and they sincerely want their customers to be happy with their watches. They don't mind at all that there are negative comments from time to time, rather they welcome the opportunity to discover ways to improve their products by listening to what customers have to say. A real mind-blower in the face of accusations that they don't care what customers think. Quite the contrary -- they are "all ears", so to speak. And in my dealings with them, I have been continually impressed with just how responsive they actually are.