The Mill Saver 5150 is a unique downhole tool designed to minimize the damage incurred on the cutting structure of mills, cutters and section milling tools. Current downhole shock subs have linear metal springs, setup at high spring rates for drilling environments. The Mill Saver 5150 utilizes multiple nonlinear fluid springs that allow the tool to be set up for the specific downhole condition expected in a given job, typically significantly lower WOB's vs. drilling. It can be configured for standard milling ahead operations or for back-reaming operations. The fast response rate fluid springs combine with the natural frequency of the work string to dampen the vibrations created by the interface of the cutting structure and fish.