brother....if you have engine oil on the outer area of spark plug ( white ceramic portion with metallic tip ) then it means that the rubber seals need to be changed which are preventing the oil being seaped onto plugs from head....
get genuine rubber 'O' shaped seals and also use some silicon to get rid of this problem....
and if the spark area of plugs is drenched with out...it means that piston rings / pistons need to be replaced as they are not containing the engine oil below combustion area resulting in burning of engine oil and smoke in exhaust....