An improved oil filter, for use with an internal combustion engine, comprises a hollow filter housing defining a chamber therein and having an inlet and an outlet with a flow path therebetween; a mechanically active filter member disposed inside the filter housing in the flow path; and a chemically active filter member disposed inside the filter housing in the flow path. The chemically active filter member comprises a plurality of composite oil additive pellets. The plurality of pellets is interconnected to form a substantially integral permeable member, and the substantially integral permeable member is impregnated with an alkaline composition. The alkaline composition is provided to counteract acidic combustion products in lubricating oil in an internal combustion engine.