Take the exhaust off and replace any "gasket" that might have been there, then find out why there is oil coming out of the thing, usually cos the rings or barrel are worn BUT it might also be that you have a bunged up exhaust, carbon build up in the rear of the exhaust can restrict the air/gas flow you need to clean it out, folks on here will know what to use to get it out, can't remember what it was we used to use, seem to remember it was washing soda back in the day but not sure now tho. Someone help out here please!!!
This works but a bit extreme.