Rebuildable Spin-on Filters is comprised of plastic can and a plastic base wherein the plastic base is threaded into the can. The filter is rebuilt by removing and replacing the filter element containing the filter media to have the base separable from the can. The trailing frustoconical surface on the base enables the base to cam the open end of the housing apart. When the base is unscrewed from the can, it allows the base to be separable from the can. In an alternative configuration, the base has a rib with a flat trailing surface that extends perpendicular to the base. There is no base surface provided for caming the open end of the can apart by engaging complimentary frustoconical portion of the groove in the can.