A structure (200) for containing a volume of lubricant additive gel (10) which is disposed within a mechanical system, in close proximity to a wear critical surface, and which is configured to provide a release of the contained additives into a flow of lubricant over time or as a function of temperature in a site-specific manner to minimize wear or reduce oil oxidation due to harsh operating conditions. The structure defines a cage or capsule with screen or mesh sides (202) having multiple perforations or openings through which the flow of lubricant may circulate. Within the contained volume of the structure (200), additives are disposed in a gel matrix (10), and are release over time or as a function of temperature, through the perorations or openings, in close operative proximity to wear critical surfaces of the mechanical system such as a bearing assembly or gear arrangement.