Greetings.  You can order oil manufactured to Hammond specs at Goff:
http://www.goffprof.com/  They are a well-known, reliable business.

A few weeks ago we purchased a 1958 Hammond C3 in excellent condition.
It hadn't been played for over 15 years, but with multiple applications
of oil the organ fired up and played perfectly with the original tubes!

Best wishes,
Tom Gregory

P.S.: Goff also has schematics for all models.