I finally got back from a service my old mans watch that he left me . Its from the mid 1950's and has a 21 jewel auto eta movement. I asked the watchmaker if it would keep reasonable time and he got a little upset telling me it was the same as used by the likes of rolex back then and will last another 60 years if serviced more than the 24 years since the last one. I forgot to ask what eta model.
In the last 48 hours it has lost approx. 7secs. although it sat in draw for the last 14 hrs.