Quick question… While I have read the postings regarding ink shelf life I am wondering if there is a way to determine how old ink is. Specifically I borrowed some selenium 2, 3, and 4 to try to experiments before my order arrives. The ink I received from my friend is packaged in the older 120 ml round bottles. I am going to be using them in new carts on an R2880 (~10ml). The inks have not been used in awhile but are sealed well in their original containers. Is the problem with shelf life separation, something more complex, or… ? If I shake them really well before filling the carts what potential issues do you see? And when the new ink arrives do you see any issue refilling the same carts with the new ink?