new motor oil in plastic bottle/container(the one the oil comes in) , give them a shake once in a blue moon. they just stay new. pop one out , wipe it , brand new. motor oil will not evaporate away.
Fully submerged like this is the only way to do it!
I have bicycle bearings & bearing cups/fittings stored in a plastic container filled with motor oil....they've sat there for 15+ years and still chrome & shiney like the day i buried them :-)
I used to do the whole plastic bag and spray/lube, but it always thins away, you find the oil is maintained in the bag, but not on the object.
Oh, another thing.....when putting them in a container (or original motor-oil bottle), throw a rag or sponge in the bottom, it'll ensure the balls/parts aren't sitting on the bottom of the container, thus fully surrounded by goop.
MM