Poor compression in one cylander at idle.

Thank you for all the input. Sounds like some engine work soon. Just in case, we will continue to run some additive, such as 'Mechanic in a Can' or Rislone in hopes of freeing up a tight ring or ?. Does any one have a high reccomendation FOR (or AGAINST) any one of the oil addatives that are available for such problems? I want to give it our best shot.
Thank you again,
Richard