Yeah, my thinking was along the same lines, ie: what was left in the reservoir (and, admittedly there wasn't much) was just as old as what I had left in the can. So, still wanting to take that initial spring drive, poured some in. The drive? Glorious...3.2 L of unadulterated, throaty, NA goodness.
I have read some posts talking about flushing/replacing PS fluid. Is that a recommended maintenance item?