The following was taken from an article by David Christianson, and is found in January 1997 American Watchmaker’s Institute’s Horological Times publication.
“Historically, animal oils and vegetable oils have been the mainstay of horological lubricants. They can be refined and formulated to have many of the ideal properties of the perfect horological oil. But they have one serious drawback as well, they become rancid and dry up. This may be a serious drawback to the watch owner, but it certainly has been beneficial to watch repairmen and, as we’ll see in a moment, it has been beneficial to the watch movement as well.
When the animal and vegetable oils begin to deteriorate, they tend to thicken as they dry out, and the movement stops, long before any wear can take place because the thickened and dried oils still maintain a protective (albeit dried) film between metal surfaces. This forced the owner to have his watch cleaned and re-oiled on a regular and frequent basis, and with this frequent service the movement continued to perform its function with very little wear over very long periods of time. It is not unusual at all to find watch movements 100 and 200 years old that show very little wear.
In search for oils that would not deteriorate in a short period of time, synthetic oils were developed that would provide many of the properties of the ideal watch oil. About a generation ago synthetics replace animal oils as the oils of choice.
Synthetic watch oils do retain their properties longer and watch movements run longer without wear than did movements oiled with animal oils. But synthetic watch oils have their serious downside as well. There is not the thickening and caking of the oil to stop the movement and force the owner to have his watch serviced before wear can take place. Synthetic watch oils, too, deteriorate but instead of thickening they tend to become more liquid, spread and evaporate over time, especially the synthetics of the recent past. The significant of this type of deterioration is that the movement will continue to run even as the synthetic oil deteriorates and evaporates (albeit less efficiently). This will continue until pivots score, often to the point of breaking and brass bearing holes wear ovoid, aggravated by dust, dirt and rust particles from leaking case gaskets and more significantly, leaking crown gaskets. Unless the owner is disciplined with a regular and frequent service schedule (and most of us aren’t), it is the worn out movement that forces the owner to seek the servicing of the watch with a resultant extensive and expensive repair bill. The jeweled bearings and highly polished pivots and other bearing surfaces will allow the watch to run without oil but with resultant wear.
The secret to a long lived watch movement is frequent cleaning and oiling, just as in the past, but now more discipline is needed. The watch itself can not tell us when it needs servicing before it begins to wear out as the animal oils of the past allowed us to do.”
By David Christianson as published in the American Watchmaker Institute’s January 1997 Horological Times
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