I replace the O ring each time with the one Mann gives, tighten to the specified torque with a quality torque wrench.

Why I am not panicking and towing my car to the dealer is - I have been crushing them for years and never had a oil pressure light come on. NOT that I don't want to do the right thing and glad I am investigating this.....

Would love to hear from one of the BMW mechanics on here to say how many come out crushed and if/how much it affects performance of the filter