Use of the mixture control in cruising flight reduces fuel consumption significantly,
especially at higher altitudes. The mixture should be leaned during cruising operation above
5000 feet altitude and at the pilot's discretion at lower altitudes when 75% power or less is
being used. If any doubt exists as to the amount of power being used, the mixture should be in
the FULL. RICH position for all operations under 5000 feet.

To lean the mixture, disengage lock* and pull the mixture control until the engine
becomes rough, indicating that the lean mixture limit has been reached in the leaner cylinders.
Then enrich the mixture by pushing the control toward the instmment panel until engine
operation becomes smooth. The fuel flow meter will give a close approximation of the fuel
being consumed.

If the airplane is equipped with the optional exhaust gas temperature (EGT) gauge, a more
accurate means of leaning is available to the pilot. For this procedure, refer to the Avco
Lycoming Operator's Manual.