P0420 code plus uses 1 quart of oil with every third gas fill up on a ford crown vic police inceptor

Question

probable causes?

Possibly just the converter or engine also?

Answer 1

P0420 Catalytic below threshold

This is catalytic convertor, The Crown Victoria is also know as a oil leaker.so you can be loosing oil instead, The best way to know if the engine is worn is with a cylinder efficiency test.