It is conscientious that the Piston ring is sold for maintenance purposes.
After 8,000 miles, the Piston ring felt worn, so I replaced it.
It was quite worn. After the replacement, the low speed torque revived and the Engine sound was
It has changed. It is a two-ring, so it is not as durable as a three-ring.
I think it should be replaced at about 5000k miles.

