Abstract: End members are provided which are identical to each other and are interchangeable for use in constructing an inline oil filter assembly of a first type including a replaceable filter element or for use in constructing an oil filter assembly of a second type including a replaceable cartridge embodying a filter element. The end members of a given assembly are interconnected by a center bolt which extends centrally through a hollow cylindrical housing of the assembly and each end member is provided with a fluid passage which forms either an inlet or an outlet passage of the assembly and which includes a portion that is located such that the bolt extends axially and centrally therethrough.