Accuracy of time on my Rolex

[Robert Henley]

Another recent post prompted me to measure how much my Datejust was off timewise in the course of a day or a week. On Sunday, October 30 I set my Datejust in sync with my Atomic clock (to the second). It's now been six days, and my Datejust is exactly in sync with my Atomic clock. So you can't get much more percise than that. I bought my Datejust new in 1990, and have not done anything to it since I bought it in 1990. It has not been serviced.

I usually take my watch off for most of the weekends while I'm doing chores like the lawn, etc. So when I set my watch this past Sunday it had wound down quite a bit but was still running. After the first day, when I checked the time against my Atomic clock I was six seconds behind. After the second day, I lost two more seconds. Bear in mind that beginning on Monday, I would have been wearing my watch most of the day so it re-wound itself automatically. I then noticed on day three that it gained two seconds of the eight seconds I had lost and today, six days later, I'm back to dead even. So it looks like it gains a couple of seconds a day while it's wound up from wearing it.

So my question is what is considered normal time loss or gain in a day for a Rolex?