w210 Oil filter canister leak

[treetops]

Hi Gents,

I have a fairly bad oil leak that appears to be coming from the filter canister cover. I have gone ahead and ordered a new cover which has to come from Germany so that will be next week.

I've checked and rechecked the cover, replaced the o-ring twice now and made sure it was on tight but not too tight(its plastic so not very tolerant of over tightening) Recently, I noticed there is a notch at the very top thread. It looks like something broke, but perhaps it is there by design. My logic says thats where the oil is coming from.

Have any of you E300 owners have this issue; oil leaking from the canister cover?

Notch circled in photos