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In self defense, no, I didn't use an impact wrench, and I always carefully hand tightened the drain bolt... the point of the post was to illustrate how if you never replace the washer it gets thin, hard and looses it's cushioning effect, which a new one indeed does have. In this way, over time the threads on the drainplug itself can become distorted and eventually strip the oilpan threads with little effort. This was explained to me by a german mechanic and I believed him after comparing the new and old drain plug and washers. The two plugs looked like different parts, though they were not. Everyone can make their own choice but ever since replacing that diesel oilpan myself I have made sure to use a new washer at least every few changes. Maybe Volvo pans and plugs are tougher than that, but I'm not going to be the one to find out.