Oil for Southbend lathe

["jilnmark" <jilnmark@frontiernet.net>]

Hello!
I finally have the lathe I have wanted for a long time - a 9" Southbend in
brand new shape.  The problem?  I don't know what oil to use.  Both the
owners manual and the plate on the machine call for 10 wt and 20 wt oil but
specifically forbid the use of "automobile oil"  Is there some reason I
cannot use the appropriate weight in non-detergent motor oil?  If not why? 
and where could I get the correct oil?   Thanks in advance for you help.
mark