Keeping it clean is probably a good idea. Maybe a light coat of light oil if you were really persnickety. But grease is probably counter-productive there since it will only serve to collect grit.
Additionally, I long ago switched all bike-related uses of Vaseline over to Crisco.
jim
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Cross Check Nexus7, IRO Mark V, Trek 620 Nexus7, Karate Monkey half fat, IRO Model 19 fixed, Amp Research B3, Surly 1x1 half fat fixed, and more...
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SB forever