Controlled release of additives in fluid systems

A seal assembly comprising:

• a fluid material-permeable membrane sized and adapted to be positioned in or near an opening in a casing defining a hollow interior containing a fluid material additive effective to provide a benefit to and soluble in a fluid material selected from the group consisting of a liquid lubricant composition and a hydraulic fluid composition, the membrane is adapted to be positioned so that substantially all of the fluid material additive leaving the hollow interior through the opening passes through the membrane;
• and
• a seal member sized and adapted to be positioned relative to the opening in the casing to prevent fluid material additive leaving the hollow interior through the opening when the seal member is intact, the seal member includes a support structure and a fluid material-soluble polymer.