Dear Dave,

In regards to your quandary, quite possibly the oil they might mean is
linseed oil.  After all, it is usually boiled in the manufacturing
process, and therefore should be able to withstand the friction heat
of the shaft's constant rotation in the bearing.

Lard and animal fat would probably heat up and smoke or smell like
bacon or whatever animal the fat was procured from (or worse yet,
become rancid).  Just a thought.

Sincerely,
D.F. Rowe
Bronx, New York