Backdate- Solution to Hydraulic problems

I tried vegetable oil, seemed to work great , pulling back as well. But 6 hour after the line, the plunger, seized, not able to push the plunger in. I tried other liquids, motor oil, yet right from the start the line does not move. Solution was to get clear elastics to help with the pull back of the plunger, seems to work great. Yet more pressure retained in systen because elesatic working against the other end, so manifold having some issues with power and pushing at higher pressure, but still works.