New Submariner 116610LN Running Fast & Slow

[AttentionToDetail]

Hello All,

I recently acquired a Rolex submariner 116610LN that’s running about 2 seconds fast per day. That's very accurate. The funny thing to me is, when the power reserve is half full, it starts losing about 1-2 seconds per day. So, if I fully wind the watch (40 full turns of the crown) and let it sit dial-up, it will gain about 2 seconds in the first 24 hours. Over the next 24 hours (the second half of the power reserve), the watch will then lose about 1-2 seconds per day. So at the end of my power reserve test, it looks like the watch has been running without a gain or loss of seconds. Is this normal? From what I know, the movement should be gaining OR losing time consistently but not both. Let me know what you think. Thanks.