Well, no machine will run indefinitely without maintenance. We generally ask customers to send their clocks this way every 3-4 years (after a full restoration) for maintenance oiling and inspection. Surprisingly few actually do. Folks seem surprised when the clock stops working after 10 years of neglect.
Recently we had a customer send an electric chime clock this way that was restored in 2010. It had ground to a halt. If you only do “maintenance” when the clock grinds to a halt, expect a big repair bill down the road. In this case, it was 75% of the original restoration cost, which isn’t bad considering prices have gone up since 2011. This particular piece required full tear down, multiple bushings and even a repivoting in the time train. The oil had failed probably 5 years ago but since it is an electric, the motor kept right on pushing things along into oblivion.
The repair bill was high. I am sure it may be sticker shock, but there’s nothing that can be done about it. This is not an uncommon thing. Most folks in this business offer a 90-day warranty—ours is 2 years, testimony to the time-tested refinement in our processes and attention to detail here. Nothing more can be done.
So we cannot be embarrassed if a clock movement goes 12 years without any maintenance whatsoever before grinding to a halt.
Unfortunately, most people have completely forgotten that vintage clocks are mechanical devices, like automobiles, or any other machine—they need periodic maintenance and inspection for maximum life, preferably every 3-4 years. There is no oil on earth that will still work the same after 10+ years; not even the most refined synthetics available. This applies especially to electric clocks and self winding clocks, which run non-stop. Spring and weight powered clocks will unwind and sometimes remain unattended, which indirectly extends their life somewhat–but not indefinitely.