it's the oil sending port on a ls1 engine. it's an aluminum piece, and aluminum engine block. the gasket with the black impregnated o-ring has been seeping. was thinking of not reusing the gasket in the pic and using some kind of gasket maker instead. what would be best? it will see oil temperatures to 250° F and it's right next to the catalytic converter so it may see 300°-400° heat from that on the outside.