A few weeks ago we were talking about how to oil certain things, and
I discovered in the bottom of an automatic piano I am presently working
on a small, very old yellow label lead squeeze tube under the motor
which says "Holtzer-Cabot Special Lubricant No. 1. (For motors with
wick oilers)." The tube also has a cutaway picture of the oiler on
these kinds of motors it is intended to work with.
It has a cast lead cap on the tube too, which dates it if nothing else
would. I think the piano company included the tube to oil this motor,
even though it doesn't use a wick oiler but waste packing.
There is a difference between waste packing and wick oiler. A wick
is a spring-loaded stiff braided cotton covered rope guided through the
oiler hole and rides in a chamfered hole flush with or touching the
The oil in the tube itself is still fresh, and looks to be very heavy,
far more-so than motor oil, but not to the point of light grease. So
I'd just guess that automobile differential oil should be about right.
To those who don't want to go buy differential lube, if you are just
re-oiling a motor now and then, a drop or two of heavy motor oil won't
hurt anything, but just enough to liquefy the old oil in the wick,
which has gotten thick with age.
In waste-packing oilers like the reproducer motors have, a little very
heavy motor oil, like SAE 40 to 60 weight oil, is fine. The problem
with thinner motor oil, like the 10W-40 found today, is that you will
eventually find it spread in a perfect circle around the belly cloth
of a grand. It usually doesn't hurt anything in a brushless motor --
it just makes a mess.