Love this discussion, wish I had something definitive to add. The range of greases available in the industrial field is mind-boggling. This is only hearsay since I haven't run any tests like Tammi but...Lubriplate 105 is a thin, smooth, cream colored grease available in small tubes; my dad (chem engineer) swore by it. Calcium based, petroleum-derived, 170F rated, good working penetration at 77F, NLGI 0. About $6 for a 50gm tube (except in Canada of course, hehe). A slightly heavier version is 130-AA.
Not modern synthetic stuff by any means but recommended for plain bearings like used in old sewing machine motors (among MANY other things). Our vintage machines and motors aren't modern or synthetic either.