A replaceable composite filter cartridge comprising: a concave and cylindrical metal housing defining an interior space having a longitudinal axis, said housing having a closed first end, an open second end and a continuous or discontinuous outwardly flared lip at said housing open second end between a first plastic end cap and a ring-shaped plastic retainer ; filter media supported within said interior space and surrounding said longitudinal axis between first and second axial ends; said first plastic end cap secured to said first axial end of said filter media and having an outside surface complementary to said outwardly flared lip , said first end cap spanning said open second end and defining a fluid inlet and a fluid outlet ; said ring-shaped plastic retainer configured to surround said cylindrical concave metal housing and including an interior surface complementary to said outside surface of said first end cap and said outwardly flared lip , the interface between said first plastic end cap outside surface and said plastic retainer interior surface being rotationally symmetrical, wherein said plastic retainer and first plastic end cap are both engaged with said outwardly flared lip and joined to each other so that said outwardly flared lip is trapped between said plastic retainer and said first plastic end cap , thereby securing said housing to said first end cap , wherein molded plastic attachment features are arranged on the peripheral outside surfaces of the plastic retainer or the first plastic end cap , so as to allow the filter cartridge to interface with complementary features on an associated filter head for securing the filter cartridge to the filter head, and wherein the plastic components are further configured to carry seals to prevent fluid leakage from within the filter cartridge at the metal/plastic interface and at the filter cartridge to head connection. a concave and cylindrical metal housing defining an interior space having a longitudinal axis, said housing having a closed first end, an open second end and a continuous or discontinuous outwardly flared lip at said housing open second end between a first plastic end cap and a ring-shaped plastic retainer ; filter media supported within said interior space and surrounding said longitudinal axis between first and second axial ends; said first plastic end cap secured to said first axial end of said filter media and having an outside surface complementary to said outwardly flared lip , said first end cap spanning said open second end and defining a fluid inlet and a fluid outlet ; said ring-shaped plastic retainer configured to surround said cylindrical concave metal housing and including an interior surface complementary to said outside surface of said first end cap and said outwardly flared lip , the interface between said first plastic end cap outside surface and said plastic retainer interior surface being rotationally symmetrical, wherein said plastic retainer and first plastic end cap are both engaged with said outwardly flared lip and joined to each other so that said outwardly flared lip is trapped between said plastic retainer and said first plastic end cap , thereby securing said housing to said first end cap , wherein molded plastic attachment features are arranged on the peripheral outside surfaces of the plastic retainer or the first plastic end cap , so as to allow the filter cartridge to interface with complementary features on an associated filter head for securing the filter cartridge to the filter head, and wherein the plastic components are further configured to carry seals to prevent fluid leakage from within the filter cartridge at the metal/plastic interface and at the filter cartridge to head connection. <EOS>