I've recently purchased my first car (2004 Subaru Legacy), and though I sent it to the shop soon afterward for routine maintenance, I want to learn and do as much as possible myself. 3,000 miles have rolled by since then, and I'm sending it to the shop again to have maintenance done (and a few details checked on).
However, I changed the oil and filter myself today, so they won't need to this time. My question arises because in doing internet research before the job, I found that it's often recommended to change the oil drain plug gasket. So far so good. But the options stump me. So far I've heard fiber, nylon, rubber, copper, aluminum, and steel referenced. There are "crush washers". Some say metal is better, some say it's worse. Some say nylon melts.
My current washer is metal and seems in good shape. The contact with the pan and plug head is smooth, and the thread of the plug is very good. I guessed it would be fine to leave it in this time.
I want to do the best thing here, but I don't know what that is.