Sudden Rate Change; I Just Don't Get It

[OneEyeMan]

I purchased a Ref 114060 Sub back in April and have worn it every day since.
My daily activity has been the same every day.
Up until about 2 weeks ago, every morning I checked it, it was either +1 or +2 sec compared to the atomic clock.
Phenomenal performance rivaling quartz which I really didn't expect.
Some weeks it was exactly on for the entire week
Then, 2 weeks ago, I checked it as usual.
It was -2 sec.
Since then, it has dropped to -5 sec total compared to the atomic clock.
This is still pretty phenomenal performance, but clearly, something changed.
I haven't dropped it, exposed it to magnetic fields (which as I understand would only speed up the rate), or otherwise abused it.
The only thing that changed is the weather. It's been unseasonably cool for these last 2 weeks.
But I can't believe that changed the rate, and I thought Rolex adjusted their movements for temp
Any thoughts as to what happened.
Thanks all,
Lenny

[gerrya]

Actually my Explorer II 216570 since new, about a year, runs dead on in summer and in winter it runs between -1 and -2 seconds slow a day.

[OneEyeMan]

Originally Posted by gerrya

Actually my Explorer II 216570 since new, about a year, runs dead on in summer and in winter it runs between -1 and -2 seconds slow a day.

Interesting.
That would kinda validate what I'm seeing.
Thanks.

[gerrya]

I live in NY and in the middle of last winter took a trip to Miami and for that 4 days it ran prefect, so that proved it for me.

[iclick]

My watches tend to run faster in warmer weather, so I wouldn't worry about your variance unless it gets worse. In fact, with one exception mine are regulated very close and it isn't unusual for my current wearer to run fast +1 or +2 for a few days then run similarly slow for the next short period.

You might be surprised how close you can keep your watches by using self-regulation, or positioning at night. Just determine by observation or a Timegrapher what the watch does in the six main positions (dial up, dial down, crown up, crown down, 12 up, and 12 down) at night. For example, the Tudor 79090 Sub I'm now wearing was set at zero 23 days ago and this morning it was at zero variance, though tomorrow it might be +2 or -1. In the interim it has varied 1-2 sec/day one way or the other and I accordingly position it to "catch up" at night. It and three of my other four watches will stay within a few seconds of zero indefinitely using this method. The exception is the Daytona which is regulated a bit fast (+5/day on my wrist), but can't be self-regulated in the long term because it runs fast in all positions. A simple internal regulation by a watchmaker would correct this but I don't bother since I don't wear it for more than a day or two at a time anyway.

All four of the other watches can be kept near zero for the long term, but not one has exactly the same characteristics and any of the others. I just have to take notes and handle them as individuals.

[StanGMT]

For what it's worth, my 1967 - vintage GMT (which I wear every day) does exactly the same here in the UK. It keeps near-perfect time throughout the summer months but, come autumn it lapses to losing around 4 sec a day until the next spring, even though I lie it oriented for maximum gain at night.

So, during winter I just leave it to lose time and adjust the minute hand forward by one division every 15 days or so.

Stan.