Is that the same as what mechanics call a "crush" washer? In my 25 years of changing oil, the cars either used a copper or aluminum washer that "crushed" under pressure to make a good seal.

The only exception was an '89 Cavelier my wife came into the marriage with. It took a special washer. It was aluminum, but also has an inside rubber ring connected to the aluminum.

dum8ss1236 mentions that he's never seen a drain plug washer on other vehicles. I have never seen one without one. I don't understand how there could be a good seal without one.

dum8ss1236 - Since the 4Runner needs a washer, you'll need to put one on (even though you'll lose a some of that synthetic oil).