O ring for filler cap

[Motorbreath]

Thanks Limax. I have found the damn 5€ ring. It is the correct size, so it is my fault, I tightened the cap too hard! I thought it could be lost otherwise. I am going to put the o-ring again...

Edit:
Yes, I am such a great mechanic! :wall The cap border is even a bit cracked, still useable, but wtf!