I got turn d on to these from another faithfull driver
The washers are cupped and the rubber seals the threads
Once on snug two times around
The cool down and resnug till the rubber pushes out flat
After a couple of days they will lock down
The are wonderful
Maybe 10 cents each
No more leaks and are way better thAn the washers with a center rubber ring
Bone dry
Good luck
Gtjoey