mineral spirits to clean bearings works well. diesel fuel isn't bad. wear gloves, mineral spirits less a carcinogen. But I like steaks and burgers too. (bad for you, considered a carcinogen too)
as for replacement grease, i just use regular old axle grease. the same stuff that's been used for the last 50 plus yrs. I guess you could use whale blubber but I don't have a chuckwagon anymore. did though.