thanks for the info, much appreciated.
The clock oils pdf is a gem! Read it over and over.
Apologies for late reply. Life got in the way for a couple of days.
There have been several similar reports on oils for clocks. Some, like this one, are mostly anecdotal observations. Others get highly technical and theoretical about principals of lubrication that may or may not transfer to the needs of the clock world. In my opinion, the final chapter is yet to be written. When reading such a report one needs to question whether the author is attempting to validate his own choice, or whether there is adequate scientific research and a large enough sample population to drawl a valid unbiased conclusion.
I have no opinion about Windles Clock Oil (and some of the others in the report) because I've never used it. It has been around for a while and more importantly I haven't heard anything bad about it.
We heard a lot of hype about nano oil, then reports of problems and finally a large movement maker that briefly adopted it suddenly stopped using it. Now we know to avoid it. The report mentioned one brand that turned pivots green, I found the same thing and I believe one would do well to avoid that. We often hear that someone has had great results with a particular oil today, but will they still be excited 10 years later? Is there something better than what you are using, probably, but what will it turn out to be.
The popular consensus is that synthetic oils are preferable, and there is some disagreement about the best viscosity for various size pivots, and whether synthetic engine oils are an adequate or possibly superior substitute for products labeled as "clock oil". I would say the jury is still out on that one. I do not believe that engine oils contain anything harmful to clocks and the anti-wear and anti-friction additive packages may be beneficial. I've often wondered is synthetic oil for reciprocating air compressors might be more appropriate. These machines are like internal combustion engines without the combustion.
For the cautious, I suggest a synthetic oil of appropriate viscosity labeled as clock oil by a well know brand. I use Nye-140 for small pivots and Mobil-1 (zero)W-20 for average to large pivots. I like Modil-1 75W-90 gear oil for mainsprings and have encountered no problems. I find it helpful to hear what others have found to work or not work.