I am a watchmaker and collector in addition to dabbling in several other hobbies, and I specialize primarily in pre-1900 American watches. Up until some time in the 1960s, THE gold standard lubricant for watches and other fine machinery was porpoise jaw oil(although sperm whale oil did see some use). In fact, the Nye lubricant company, which is still around, built their business on porpoise jaw watch oils. Hamilton developed their own synthetic oils in-house in the 1940s, and Elgin in the 1950s. The Elgin synthetic product is quite well regarded, even today. I have probably a 1 1/2 mL of it, which realistically at the rate I use it is probably enough to last the rest of my life. I use it for most of the train jewels in pocket watches, and it continues to be a super lubricant for those(I have some special Swiss magic pixie dust lubricant that costs $40 per 1/2mL for some special purposes, but the Elgin oil is my go-to).
In any case, one nasty habit of animal based lubricants is that after 100 or more years, many of them have gone rancid and congealed into a solid, crystalline mass. I've taken apart watches where it took a fair bit of effort to even get pivots out of jewels, and have broken a handful over the years in the process. Once out, the only real way to get rid of the old oil is to physically chip it off-as a watchmaker, one of your key tools is a stick of peg wood that is sharpened continuously both to expose a clean point and to shape it to a specific application. In any case, I will often sharpen to a chisel tip and scrape the face of the jewel, followed by a point to clean the hole. Running a watch with congealed oil like this through a cleaning machine usually will scarily touch the old porpoise jaw oil-it might soften it up, but you still need to physically remove it. It can take me an hour of manual work to get a 23j railroad watch to where I'm happy with it.
Fortunately at least in watch applications the biggest enemy to synthetic oils(which are now the only thing widely available, with the exception of tallow-based greases) are dust and migration. Using the correct amount of oil(usually less than you think you should use
) and matching the viscosity to the application(one of the reasons why the Moebius lubricant company catalogs about a half dozen different train oils) will minimize migration. The cases on most modern wristwatches do a good job of keeping dust out. The Rolex Oyster case really is the gold standard here, or at least was the first truly successful one, and depending on who you ask a good condition Rolex case will allow you to go anywhere from 5-10 years of daily wear without servicing. Most of the better manufacturers now specify service intervals in that same ballpark.