This problem would never happen if people would just do 3 things correctly when they change their oil:
1) If the head of the bolt is even slightly worn replace it!!!
2) Make sure the washer that is supposed to be on the plug is there when you put the plug back in.
3) Don't over torque it when you put it in, instead of a big ratchet, extension and a socket use a short combo wrench you have to be real gorrila to overtorque it with a little combo wrench.
Now if I just had a solution for the stubborn oil filter!!!!
1987 190 Euro