You can reuse copper crush washers if you re-anneal them. (Heat them with a mapp torch to white-hot and quench in water) Just FYI if you need to in a pinch.Crush washers are definitely one time use. But my experience is that the replacements that come with new fuel filters/pumps aren't right. If the washer is too thick (outside minus inside, not height), then it takes more force to crush/seal than you can provide without stripping out threads. I picked up a kit of aluminum crush washers on Amazon a few months ago just because of that. Aluminum also crushes easier than copper. Works for all the times that you forget to buy replacement crush washers for the oil drain plug, as well.