I have a 1985 Crown Victoria

Oil pressure sender. Cheap part, just replace. Wipe area off of oil and grime so you don't get any in threads. Pull wire off of end gently, use open ended wrench to unscrew component. If new component has thread sealant already on threads simply thread by hand until finger tight then seat firmly with wrench. If no sealant already just use three wraps of teflon tape. Reattach wire, start car, check for leaks.

if its about the size of a silver dollar and has a wire hooked to it, it sounds like the oil pressure sending unit. Silver in color.