For our experienced watch repair folks...

1. Do synthetic oils spoil or go bad over time?

2. I have heard some say that it is OK to use petroleum jelly for lubrication of the winding components / parts of a pocket watch. What are your thoughts or comments on this practice?

Thanks for your input!

Serge, Synthetic oils of low and higher viscosity crafted for lubricating watch movements and mainsprings can offer several decades of good performance in a clean environment. Petroleum Jelly can harden and I would not use it in any watch for any reason.

The "lifetime" of watch cleaning and lubricating is governed by how quickly it becomes filled with foreign particles of airborne debris. Generally a daily "carry watch" may become unreliable after 2-5 years, depending on if you carry it in Peking China or Red Lake Minnesota, USA.

In all cases, effective watch lubrication is only accomplished AFTER the watch has been carefully cleaned and inspected.

Thanks for your input David, I appreciate it!

I used synthetic oils for over two years. I had a unit returned because the Escape system was dry. I ignored it because I thought maybe I just forgot to oil those parts (Unlikely).
Then I fell and broke my hip and was in a hospital for three months
and after being released fell again and broke 2 ribs. Another month of convalescing and finally I was back at the bench. I dipped my # 2 oilier in the well and placed it on a part. Nothing, no oil. looking in the well it was bone dry. The well next to it still had plenty of oil in it, so I used it.
(Moebius / 8000) In my opinion,The synthetic stuff is not for longevity.
I checked an Elgin 18s I did two years ago and still had in my collection and it is absolutely drier than popcorn flatulent.
I now have a outlet for Moebuis/8000 in a 10 ML bottle (Thats a lot of watch oil) The bottles are dated so you know how old it is.