After earlier posts about this issue, I changed mine on my Ed30. Its not a high mileage car, but for £30 or so its a no briner to swap. Mine was just starting to show signs of the black coating wearing.
After swapping it the engine is noticeably quieter.
For a 15 min, super easy job to swap *, its a no brainer to put your mind at ease. And remember, its not mileage its the number of revs the engine has done that wears the part.
*I wouldn't be bothered swapping the O ring, its £16 + VAT!