SylvanLMP
The only thing I would suggest have your oil burner repair guy make an efficiency test of your burner for proper combustion and possibly a high out burner like a Becket or Sunray if the burner box is in good shape this alone could say you a small fortune
Let them take the CO reading a stack temperature tell him you want the flame nozzle properly adjusted and a new filter) oil) installed. Watch how the serviceman works and ASK QUESTIONS RE your system.
Good luck
