Lady Datejust power reserve

Hi folks. I'm sorry if this is a daft question, but is the Lady Datejust (26mm) automatic? If so, what kind of power reserve should I expect. It'll last a few days once wound up. Thanks in advance.

You don't say exactly which era the watch is from, but I'm going to assume 1983-2015 (given 2015 was when the 26mm was discontinued in favour of the 28mm with a newer movement), and so it's likely to be using a Rolex 2135 which is indeed an automatic movement.

From what I can see the power reserve should be 42 hours.

Thanks a million. Yes, it’s pre ‘15, would a service improve the reserve or is she just not ‘jiggling’ it enough?

Since you say it lasts a few days once wound, that implies if stops after more than just the base 42h - correct?

If so then the automatic works are winding the movement some, but not enough to keep the watch at a decent state of wind and hence running continuously. If this is a new thing (i.e. the watch is stopping or needs handwinding to keep running), then sounds like it needs attention.

If this has always been the way (and by “always” I mean when the watch was new or recently serviced and hence in a good state of repair), then maybe more jiggling is required, but I’d expect most folk be able to keep an automatic going.

How long has it been since it was serviced? A watchmaker should be able to put it on a timegrapher and tell if the movement itself is performing as expected and if not, that’s another reason to look at a service, but that is a separate concern to the effectiveness of the automatic winding.

I worked with a girl who had 3 different Rolex watches she wore in rotation. She moaned to me they kept stopping after a day or so - I suggested she hand wound them before putting them on. She had no idea she could, problem solved!

Thanks folks, she wears the watch daily but I'm going to have to tell her that her pace of life is too sedentary!