I just sold my gen 2 Prius. Right before the buyer took it away, I changed the front rotors (pads were new and not changed) and topped off the engine coolant reservoir. After the car was driven off, I swept the garage floor and found this rubber gasket. It may or may not have come from the Prius. Can anyone identify it? It's 40 mm in diameter and 1.5 mm thick. The white substance may be dried white grease. Thanks!
It looks like a screw capture washer - nothing important.... A sealing washer wouldn't have those cut-outs near the center of the hole.
Thanks for the input, but so far my only guess is that it's a rubber insert on the inside of the cap for the coolant reservoir tank. Since I don't have the car anymore, could someone take a peek and see if there's a rubber insert like this in the cap? Many thanks!