Please note other vegi oils arent as good as castor, depending on which is used you may get more varnish buildup or other undesirable things happening , there is a simple method to give other oils some of the castor oil traits, the results depend on the base oil used( I'll make no recomedations). See this post for more details :-
http://www.rcuniverse.com/forum/m_45...4/key_/tm.htm#
I'ed suggest some testing befor commiting to its use, preferably in a run in motor that you consider disposeable.
Stewart