I once bought "green" mineral spirits by accident because it was on deep discount so I didn't look at the label. Why don't they just call it something else? Reminds me of when I needed TSP for something, and all the store had was "phosphorus free TSP." What the hell is phosphorus free trisodium phosphate?
Anyway, I've stored chains in mineral spirits indefinitely. I used to take the chain off my winter bike at the end of the winter, drop it into a jar of mineral spirits, and take it back out the next winter. In terms of chemical reactivity, I don't think it's substantially different than oil or even wax.