Abstract: An oil filter cartridge comprising filter discs and separator discs stacked alternately, the separator discs having inlet and outlet chambers walled in by the contiguous filter discs. The filter discs have inlet ports in registration with the inlet chambers for introducing unfiltered oil therein. The separator discs are provided with slots registering with the inlet ports of the filter discs. These slots, in combination with the adjacent inlet ports, provide enlarged inlet orifices which are not readily blocked by swelling of the material of the separator discs due to water-contaminated oil.