Teflon coated Toyota oil drain plug washers.I picked up some of these for the drain plugs on our Scion xB's....
And since I could never find genuine 'crush' washers for the scooter oil changes, I tried one of these and it works great on the 17mm drain bolt of my LIKE200i! Teflon coated on both sides of the aluminum washer - seals with a gentle snug of the wrench. Easy off because of the Teflon coating.
A genuine 'crush' washer does just that: crushes and seals wiithout a great deal of torque to the drain bolt. (found on spark plugs, and very few other places these days)
Various sources for these Teflon washers used on Toyotas: Amazon and eBay have them. I paid less than $6 for a pack of 10.
Stig
Washer seen here on my LIKE's 17mm oil drain bolt.