stem seals by far, this is a bit of a patch job ut with limited tools it should help rule out rings, go to supercheap and buy some "liquid molly engine oil re sealer " if the smoke starts to go away or gets less there is a pretty good chance it is your stem seals and for $14 its cheap enough to give it a go anyway, it will not last but might get you out of the poo for 6 - 12 months if your lucky but this is just a band aid and it will still need to be fixed. it takes between 20-200km for it to work. it worked on mine but like I said its a band aid