The concern about synthetic lubricants has little merit.  First,
synthetic lubricants such as "Mobil 1" do not contain silicone or
Teflon.  Second, it is not very difficult to remove silicone from
finishes.  If it migrates into the wood it would be difficult to remove
but unless a huge amount got on the raw wood, it would not likely
interfere with subsequent finishing because the wood would absorb
the first coat of the new finish.

Silicones are a problem on car finishes if painting is done with no
concern for their presence because they prevent adhesion to the old
finish and also migrate into the new finish.  VM&P Naphtha removes
silicone from hard finishes.  It is the main ingredient in all silicone
removers that professional car finishers use.

If you suspect a large amount of silicone has soaked into raw wood
(not likely on a piano) it would probably suffice to apply a coat of
clear shellac before the final finish.  Shellac will not "fish eye"
with silicone.  If you want to use polyester or some other or other
modern catalyzed finish you probably can not use shellac under it,
but why would anyone put such a finish on an antique piano?!

Spencer Chase
Edmonds, Washington