A 172sp with high oil consumption #2 lower plug wet with oil. 25 hours ago it fouled the plug. A student brought it in last week saying it would not pass mag check, pulled number two for rings and hone. The cylinder has been a problem since new. Reinstalled cylinder and sent the airplane on a long cross country to break in. mag drop compaint again. pulled # 2 lower wet with oil and cleaned, no fix. pulled the remaining plugs and found 3 upper dead. Changed plug and all was fine, just because you know the engine don't assume.