I changed the oil on my friend's 1997 Del Sol. I bought a crush washer for it along with the filter and Mobil Clean 7500. I handed him the crush washer and told him not to lose it. I removed the oil drain plug (which required using a 1 foot ratchet..which should've been my clue that something was wrong..) and I couldn't get the crush washer off of it. Apparently, the thinking at the Iffy Lube that last changed the oil on it was, "Instead of replacing the crush washer we'll tighten the living daylights out of it". So we had to go to Autozone to get a new drain plug, and in the process he misplaced the new crush washer..and Autozone didn't have any. So I just got a new drain plug and a rubber/metal gasket and put it on and it seemed to work fine. (They were out of the Motormite drain plug their computer listed for the Del Sol, but the box listed the actual thread size and they did have a drain plug of another brand in that size, so I got that instead). So I ask, why crush washers? What benefit do they offer over a rubber/metal gasket? Why wouldn't someone want to use a rubber/metal gasket instead of a crush washer?