> Walnut oil

There's a longish list of vegetable oils that can do the trick.  
Unboiled linseed oil for one, which *is* used, believe it or not, in 
some food recipes.  Grapeseed oil won't go rancid either.  And there's 
always the lemon oil or orange oil and bees wax solutions that are used 
as furniture polishes. These are great for the channels of double hung 
windows (we do know that these channels should never be painted).
There's another vegetable oil I've used in the distant past that won't 
go rancid, safflower oil.  Takes a while, but will eventually harden.

Mike in Sacto