troubler

when having trouble starting my car i got it checked by a mechanic who said that there was oil in my spark plug so he changed them and it was fine till now a month later so i went to the same mechanic and he was on leave so i went to some other guy who said that the spark plugs need to be changed again as there is oil so i explained the same thing to the mechanic NO 2 that they have been changed a month back and it the oil issue to which he didnt agree with me now what do i do where is the dam oil coming into my spark plugs hellppp