Definitely use non-detergent oil in anything with a bronze bushing (starters, distributor oilers, commutator end of the generator, etc).
More than a few reliable electric motor people have told me that detergent oils will "seal" the pores in the absorbent bronze bushing, and it will actually run "dry".
"3 in 1" Electric motor oil is essentially SAE 20, non-detergent oil, in a convenient little package.
