Ok I'll correct you. You are wrong. Read the above.
In the scenario you mention, NC has a look and finds that one of the rocker drain tubes has a loose union nut so he gets out his trusty Halfords adjustable spanner and tightens the nut. However, he does not realise that the elbow fitting, the nut and the tube are manufactured from a light alloy and he introduces a stress crack in the flange of the tube or manages to introduce a twist in the tube down near one of the bends. X number of hours later a carefree Mr X along with his mate and 2 kids is enjoying his expensive trip out to the cafe in the same aircraft when suddenly he notices the oil pressure is very low and the oil temp has risen through the roof. He sees no other sign of the pending mishap until suddenly the engine starts to run roughly and then seconds later it seizes just as he's about to cross a large urban area. The innocent little adjustment made X hours before has resulted in the tube giving way and emptying the engine oil contents into the lower cowling. Hope Mr X's PFLs are well practiced and up to scratch and that he's been a very conscientious pilot and made sure that he could safely land clear before setting out on his direct track across the large conurbation.