5513 1520 movement aptitude

[Nickn]

I wa given a new timer for Christmas and whilst waiting for dinner am timing my watches
This 1976 5513 bought at an antique fair for £20
And no I didn’t run back and offer more when I found out it was genuine
Has never had a service but keeps near 0 time on the wrist
How do these readings look?
I would have thought the aptitude should be higher?

[Nickn]

The +3 second is when I first wound the watch and put it on the machine

[Nickn]

Results

[Nickn]

Just got similar results from another 5513
But 1680 had an aptitude of 270 -4 sec

[SearChart]

That is not a good amplitude.

[Nickn]

Is it Strange it’s keep good time ?

[SearChart]

Originally Posted by Nickn

Is it Strange it’s keep good time ?

No, that is not strange but it is uncommon.

There's probably some wear and tear on pivots, all lubrication is dried up which lowers amplitude significantly.

Even though it still keeps good time you're letting it run while it is not properly cleaned and lubricated, which will result in it wearing out even faster.

[Nickn]

After 46 years it deserves a service I’ll book it in
Interestingly ,for me at least, the watch that was keeping the most accurate time out of the 50+ watches I timed was smiths w10 17 jewel from 1969 0 sec 270 apt