Novel filter elements for sequestering acids from oil or fuel, the strong base flocs that comprise the filter elements, and methods of their preparation and use are disclosed. The filter elements comprise a mechanically linked interlocking fiber matrix interspersed with strong base particle flocs wherein the strong base particles constitute at least 30% by weight of the filter element. Certain filter elements may be useful for sequestering acids or neutralized acids in certain oils or fuels, for example, the acids originating in the combustion and lubrication system of an internal combustion engine or those contained in oils in an oil circulation system. Other filter elements may be useful for reducing oxidation of an oil.