Why would my 2003 jaguar x-type oil pan leak?

Assuming you get regular oil changes you could have a cracked or split washer on the drainplug which will cause a leak. Else, you 've disturbed the oilpan itself and its leaking from the gasket that seals the pan to the bottom of the engine block. Causes of this can be using a trolley jack on the pan to lift the car, hitting the oilpan with kerb or raised manhole cover etc.. You don't need much force to knock the pan and outta alignment and disturb the seal. Repair.. replace the drain plug.. or replace the gasket and the bolts that hold the pan in place. Difficulty.. easier in a garage with a car lift.. 15 mins.. 25 mins on jackstands