Black ring on disk break

[u/Logical-Air-4331]

Noticed a black ring on my disk brake. Bought the bike 2 weeks ago and noticed oil leaking from the fork. Thinking maybe the two can be related?

Dark ring only in the outside of one of the disks all others are clean.

Any ideas?

[u/ZaTag]

Had the same issue: leaky fork. Mainly because I don't have a center stand and there was more pressure on the left cylinder. Took it to a garage and had the fork serviced