A container for releasing a microbiocide component into a liquid composition susceptible to unwanted microbial growth (LCMG) includes a LCMG impermeable casing separate and apart from an internal combustion engine filter housing, and having a hollow interior and at least one opening. A microbiocide component, for example, at least one LCMG-soluble microbiocide, as the only active material located in the hollow interior. At least one liquid permeable element, for example, a membrane member, is provided at or near an opening in the casing and is effective to provide for release of microbiocide component into the LCMG. Methods of releasing microbiocide component into LCMGs are also provided.
