WHAT'S THE BEST LUBE FOR A URETHANE BUSHING................

Hotchkis super grease Hotchkis Sport Suspension Super Grease 3101

If you don't have greaseable pivot pins then you can use the little tubes Prothane Super Grease 19-1750

Whatever you do don't use dielectric grease. As far as cleaning, I would try to avoid using any harsh cleaning chemicals. A little wd-40 should clean it up fine though.

***Edit***

Looks like rob beat me to it with the little tubes of prothane grease!