They are crush washers and intended to be one-time use. It's a different style crush washer than the copper oil pan ones but too cheap to not replace IMO. I'll bring a dozen of them to ZDayZ for you, Spooler.
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2011 370Z 6MT Sport Gun Metallic | ARC | CJM | Ecutek | FI | Fujimura | R2C | SPL | Stillen | TWM | Z1 | ZSpeed | |