I was talking shop with an older guy who maintains his business vehicles and got on the topic of reusing drain plug washers. He recommends the copper type over the aluminum ones, as the former can be reused more times than the softer aluminum type. And if you're in a pinch for a washer, he says, make one out of the plastic jug the oil came in! Use a thick flat section and don't double gasket. I ask, but won't the engine heat make the plastic melt or soften? He replies not so. He says he's even reused the same plastic gasket he's made 2 or 3 times on successive oil changes, no problem. And he's been doing this for years, he claims. And no, I don't think he's pulling my leg.