Yup, one washer lasted 40k miles, but I change oil every service (might as well, I like to treat my engine
). So that's around 10-12 oil changes it's survived.
But yes, I also use PTFE (on the very end of the threads - not the tip of the bolt - by the head, before anyone shouts about it being dangerous etc).
The sales guy didn't even think they had sump washers until I said "If I can tell you where they are will you buy it for me?" - at that point he asked one of the mechanics.
