I usually use Penn Reel oil and grease. Everyone's suggestions will most likely work fine, one option might last longer than another but as long as you keep up on regular maintances that shouldn't matter. However I would recomened not using rust penatrent oils such as WD40 or PB Blaster since these have a tendancy to damage seals and synthetic material. I wouldn't use White Lithium either since it gets abbrasive as it ages and dries out.