Scary though this maybe for some, I am the owner of a grease gun which has been used

Surfing about on the bay, thought I would look to get a new cartridge to put into stock. Seems to be a couple of different types, basically general purpose or lithium. Probably more.
Question to my betters is, is there any benefit to buying the dearer lithium stuff or stick with the general purpose stuff ? Would it be OK to use lithium in UJ's & the like where the general purpose stuff has been used before & still in the joints ?
I await further education