This should be a 4 stroke petrol engine.
Assuming no one has tipped the mixer so the sump oil gets elsewhere inside the engine, that means it could be a broken oil control (bottom ring) piston ring. The engine is probably a Briggs and Stratton
Google search:"piston rings for briggs and stratton" and there are loads of choices. Dont forget to quote your engine number and buy a replacement 'head gasket'
GB in Wales, February 2013
