Join Date: Feb 2017
Location: Vancouver Island-Canada
1st, ensure the source of the oil has been corrected.
2nd, remove caliper and pads from caliper and clean up excess oil.
3rd, get some green or red scotch-brite and brake clean and de-glaze the rotor (see YouTube)
4th, brake clean the pads maybe even a few times.
5th, put it back together and see how they feel.
A set of pads are cheap in the US so I wouldn't hesitate to replace them but the above should be suitable until new pads arrive.